Frank ICSE Solutions for Class 10 Chemistry – Chemical Bonding

Frank ICSE Solutions for Class 10 Chemistry – Chemical Bonding

PAGE N0 : 39
Solution 1:
Chemical bond: A chemical bond may be defined as the linkage that stands for the force which actually holds the atoms together within the molecule.
Chemical bonding: The phenomenon during which a chemical bond is formed is called chemical bonding.

Solution 2:
Atoms combine to attain the electronic configuration of nearest inert gases as the atoms of inert gases are very stable having 8 electrons or duplet (or 2 electrons in case of helium atom) in their outermost shell.

Solution 3:
Electrovalent compounds: The chemical compounds containing electrovalent bonds are called electrovalent or ionic compounds.
For example: Sodium chloride (NaCl).
Covalent compounds: The chemical compound, formed as a result of mutual sharing of electrons or electron pairs thereby establishing a covalent bond is called a covalent or molecular compound.
For example: Hydrogen molecule (H2)

Solution 4:
The conditions for the formation of an electrovalent bond are:

  1. Low ionization energy of electropositive atom
  2. High electron affinity of the electronegative atom.
  3. Large electronegativity difference.
  4. High lattice energy.
    Concept Insight:

    • Lower is the ionization energy of atom, higher is its tendency to lose electron to form a cation and form ionic bond.
    • Higher the value of electron affinity of an atom, greater will be its tendency to form anion and form ionic bond.
    • If the electronegativity difference of two elements is higher, more easy will be the transfer of electrons and hence more chances of ionic bond formation.
    • Lattice energy is the energy released when positive and negatively charged atoms called ions come closer to form a crystal because the attractive forces among the oppositely charged ions tend to decrease the energy of the system. Higher is the lattice energy, greater will be the ease of formation of the compound.

Solution 5:

Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 1

Solution 6:
Hydrogen chloride has a polar covalent bond because in hydrogen chloride the higher electronegativity of chlorine atom attracts the shared electron pair towards itself. As a result, the chlorine atom gets a partial negative charge while the hydrogen atom gets a partial positive charge. Hence such a covalent bond with charge separation is called polar covalent bond.
While methane has a non polar covalent bond because in case of methane molecule the shared electron pairs are at equal distance from the carbon and hydrogen atoms, because neither the carbon atom nor the hydrogen atom has enough electronegativity difference between each other to attract the shared pairs of electrons towards itself. Hence no charge separation occurs in the covalent bond due to which it is called non polar covalent bond.
Concept Insight: When a covalent bond is formed between the atoms of the same elements of equal electronegativity then the electron pairs are shared equally between the atoms and the bond so formed is called non polar covalent bond. On the other hand, if the covalent bond is formed between atoms of different elements, with difference in electro negativity, the electrons are not shared equally between the atoms. The more electronegative atom pulls the bonded pair of electrons towards itself and acquires negative charge while the other less electro negative atom acquires positive charge and the bond becomes polar covalent bond.

Solution 7:
In terms of electron transfer, oxidation is defined as the phenomenon in which an atom loses electron to form a positively charged cation while reduction is defined as the phenomenon in which an atom gains electron to form a negatively charged ion called anion.
During formation of ionic bond one atom undergoes oxidation while another atom undergoes reduction.

PAGE NO : 48
Solution 8:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 2

Solution 9:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 3

Solution 10:

  1. Sodium chloride dissolves in water because it is an ionic compound and water is also a polar covalent compound. Water decreases the electrostatic forces of attraction among the sodium and chloride ions due to which these ions become free in water, hence sodium chloride dissolves.
    On the other hand, carbon tetra chloride has non polar covalent bond and water has polar covalent bond. Hence, water is unable to break the non polar covalent bond of carbon tetra chloride. So it is insoluble in water
  2. Helium does not form Hemolecule as it has its outermost shell complete i.e. two electrons in its valence shell. Due to this complete valence shell helium atom is very stable hence does not participate in chemical bonding to form  Hemolecule.
  3. Pure water does not conduct electricity because it has a polar covalent molecule hence does not have ions in it which can conduct electricity.
    On adding sodium chloride to pure water, sodium chloride breaks apart into sodium and chloride ions because water being polar decreases the strong forces of attraction among sodium and chloride ions. Now, pure water has ions present in it which can conduct electricity.
  4. Clis a non polar molecule because the bond is between same atoms that is chlorine with zero electronegativity difference among them. So the shared electron pair is attracted equally by the two chlorine atoms hence there is no separation of charges in the bond formed so the chlorine molecule is non polar.
  5. In case of HCl the bond is formed between two different atoms that is hydrogen and chlorine with enough electro negativity difference so that the shared electron pair is attracted towards more electronegative chlorine atom which acquires partial negative charge while the hydrogen atom acquires partial positive charge hence HCl is a polar molecule.
  6. Metals have low ionization energy due to which they can lose their outermost electrons easily to form positive metallic ions hence metals are electropositive.
    For example Sodium metal always form Na+ions, Potassium forms Kions etc.

Solution 11:

  1. (i) when the electro negativity difference between the two atoms is high then the bond formed will be purely ionic.
    (ii) When the electro negativity difference between the two atoms is low then the bond formed will be polar covalent bond.
    (iii) When the electro negativity difference between the two atoms is zero then the bond formed will be purely covalent.
  2. Ionic compounds = NO, NH4Cl, NH4NO3
    Covalent compounds = N2, NH2 , NO
    Polar compounds = NCl3

Concept Insight: Electro negativity difference between the bonded atoms determines the ease of transfer of electrons between the atoms. On the basis of extent of transfer of electrons between the two atoms the bond will be ionic, covalent or polar.

Solution 12:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 4

Solution 13:

  1. MgCl2, CaCl2.
  2. Urea, Glucose.
  3. CH4, benzene.
  4. SO2, H2S
  5. H2, N2

Solution 14:
The necessary conditions for the formation of covalent molecule are:

  1. Number of valence electrons: Both the participating atoms should have four or more valence electrons in their valence shell.
  2. Equal electro negativities: The combining atoms should have equal electro negativities so that no transfer of electrons takes place.
  3. Equal electron affinities: The combining atoms should also have equal electron affinities i.e. equal attraction for electrons.
  4. Ionization energy: It should be high for both the atoms so that there is no chance of removal of electrons.
  5. High nuclear charge and small inter nuclear distance: Both these conditions favor the formation of covalent bond because during the formation of a covalent bond the electron density gets concentrated between the nuclei of the combining atoms and this electronic charge is responsible for holding the two nuclei together.
    The properties of covalent compounds are:
  6. Nature: They are generally volatile liquids or gases. Some may be gases like urea, sugar etc.
  7. Low melting and boiling points: Since the intermolecular forces of attraction are weak, very small amount of heat energy is required to overcome these forces hence their melting and boiling points are low.
  8. Electrical conductivity: Since covalent compounds are made up of molecules and not ions, so they do not conduct electricity.
  9. Solubility: These are insoluble in water but soluble in organic solvents.
  10. Ionization in solution: These do not ionize when dissolved in water except some polar covalent compounds like HCl.
  11. Molecular reactions: These participate in reactions as a molecule so the reactions are called molecular reactions. These are slow reactions.

Solution 15:
Coordinate bond: The bond formed between two atoms by a pair of electrons, provided entirely by one of the combining atoms, is called a coordinate bond or dative bond.
Conditions for the formation of coordinate bond:

  1. One of the two atoms must have at least one lone pair of electrons.
  2. Another atom should be short of at least a lone pair of electrons.

Solution 16:
Lone pair: A pair of electrons which is not shared with any other atom is known as the lone pair of electrons.
For example in NH3, Nitrogen has a lone pair of electrons which is not shared with any hydrogen atom.
Shared pair: A pair of electrons which is shared with other atoms to form a bond is known as shared pair of electrons.
For example in HCl the pair of electrons responsible for bond formation between H and Cl is called shared pair.

Solution 17:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 5

Solution 18:

  1. The forces of attraction between the molecules of covalent compounds are weak because the molecules are neutral. So, they are generally gases or liquids or soft solids.
  2. Covalent compounds have low melting and boiling point because the intermolecular forces of attraction among the molecules of covalent compounds are weak. Hence very small amount of heat energy is required to overcome the attraction between the molecules.
  3. On the basis of principle like dissolves like we can interpret the insolubility of non polar covalent compounds. Since water is a polar covalent compound that is it has positively and negatively charged ends but the non-polar covalent compounds do not have any kind of charge separation. So water molecules are unable to interact with the molecules of non polar compound and break apart the intermolecular forces of attraction among non-polar molecules making them soluble in water.
  4. Polar covalent compounds are good conductors of electricity because when these are dissolved in water, they ionize and act as electrolyte to produce ions which are responsible for conduction of electricity.
    Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 11
    For example polar covalent compound HCl in water behaves as:
    These hydronium and chloride ions produced on dissolution of HCl in water are responsible for conduction of electricity.

PAGE NO : 41
Solution 2002-1:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 6

Solution 2004-1:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 7

Solution 2005-1:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 8

PAGE NO : 42
Solution 2006-1:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 9

Solution 2006-2:

  1. (b)
  2. (a)

Solution 2007-1:
Frank ICSE Solutions for Class 10 Chemistry - Chemical Bonding 10

Solution 2008-1:
ionises when dissolved in water

Solution 2008-2:

  1. Covalent bond.
  2. Co-ordinate bond

Solution 2009-1:

  1. solid
  2. low

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Frank ICSE Solutions for Class 9 Chemistry – Elements, Compounds and Mixtures

Frank ICSE Solutions for Class 9 Chemistry – Elements, Compounds and Mixtures

PAGE NO :41
Solution 1:

  1. Elements: An element is a pure substance which can neither be broken down into simpler substances nor formed from two or more simpler substances by any known physical or chemical process. It is made of only one kind of atoms. It can be divided into four main categories
    1. Metals-Iron, magnesium
    2. Non-metals-Hydrogen, oxygen
    3. Metalloids-Arsenic, antimony
    4. Noble gas-Helium, neon
  2. Compound: A compound is a pure substance that is composed of two or more elements chemically combined in definite proportion by mass.
    The physical and chemical properties of a compound are different from those of its constituent elements.Hydrogen gas is combustible and oxygen is supporter of combustion , their  compound water  which is liquid is neither combustible nor a supporter of combustion.
  3. Mixture: Mixture is a physical combination of two or more substances, whether elements or compounds, which are mixed in any proportion by mass and retain their original properties even after mixing.
    Homogeneous mixture: They have same composition  and the same properties throughout their entire mass. Example- Salt solution, alloys etc.
    Heterogeneous mixture: They have different composition and different properties in different parts of their mass. Example-Mixture of sand and salt, mixture of iron fillings and sulphur etc.

Solution 2:

  1. Oxygen
  2. Carbon, hydrogen, Oxygen
  3. Mercury, Bromine
    1. Helium
    2. Oxygen
  4. Gallium,caesium
  5. Two noble gases are-
  6. Helium
  7. Argon

PAGE NO :42
Solution 3:
Air is a mixture because-

  1. The composition of air is not fixed i.e. the components may be present in any proportion by mass.
  2. Components of air i.e. nitrogen, oxygen etc. do not react with each other.

Solution 4:
Elements – Lead, Mercury, Sodium
Mixtures – Air, petrol, ink, gunpowder
Compounds – Common salt, alcohol, sand

Solution 5:
Pure substance – A pure substance is one which is made up of only one kind of particles. These particles may be atoms or molecules.
Example-Sulphur,  water.
Impure substance – They are mixtures of two or more chemically different substances mixed in indefinite proportions. The constituent substances retain their properties in the mixture.
Example-Mixture of salt and sand, gunpowder

Solution 6:
Mercury is the metal which is liquid at room temperature and bromine is the non-metal which is liquid at room temperature.

Solution 7:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 1

Solution 8:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 2

Solution 9:
Two reasons for believing that copper is a metal and sulphur is a non-metal are:-

  1. Copper is malleable and ductile while sulphur is neither malleable nor ductile.
  2. Copper is a good conductor of heat while sulphur is not good conductor of heat.

Solution 10:
Metalloids – The elements which possess properties intermediate between those of the metals and non-metals are called as metalloids. They react with both acids and alkali’s to form salts.
Ex – Arsenic, antimony

Solution 11:
Graphite is a non-metal which is a good conductor of electricity.

Solution 12:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 3

Solution 13:
Mixture is the general name of the materials which contain atleast two pure substances and show the properties of their constituents.

Solution 14:

  1. Sodium
  2. Bromine
  3. Arsenic
  4. Radon
  5. Mercury
  6. Oxalic acid
  7. Carbon dioxide

Solution 15:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 4

Solution 16:

  1. simpler substances
  2. atomic
  3. same
  4. mixture of salt and water
  5. two

Solution 17:
Names of two other mixtures which contain elements only are-

  1. Bronze
  2. Duralumin

Solution 18:

  1. A Molecule – The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms.
  2. Atomicity – Atomicity of an element is defined as the number of atoms present in one molecule of that element.

Solution 19:
Since, the constituents of a mixtures may be present in varying proportions so it cannot be expressed by a fixed chemical formula.

Solution 20:

  1. Air
  2. Cement
  3. Milk Sugar solution

Solution 21:
If a mixture of powdered iron and sulphur is heated in a test tube, a black shiny compound iron(II) sulphide (FeS)  is formed.

Solution 22:

  1. Tungsten, Mercury
  2. Graphite, Iodine

PAGE NO :43
Solution 23:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 5

Solution 24:

  1. Chromatography – The chromatography is a technique of separating pure substances from the mixture.
    Advantages of chromatography –

    1. It requires a very small amount of the substance or sample.
    2. The components retain their individuality during the process.
    3. Chromatography finds application in easy separation of substances with similar physical and chemical properties.
  2. Filtration – It is a separation technique for separating a mixture in which one component should be solid and insoluble in the other liquid component.
    Example- Barium sulphate  in water.
  3. Fractional distillation – It is a technique used to separate  two liquids which dissolve in one another.The separation relies on the differences in boiling points of the two liquids.
    No, mixture of chloroform and water cannot be separated by this method.
  4. Centrifugation – It is a method for separating the suspended particles of a substance from a liquid in which the mixture is rotated at a high speed in centrifuge machine.
    Application – The clay particles in water (which are very fine) can be separated by centrifugation.

Solution 25:

  1. The vapour state which is obtained by heating solid without passing through liquid state is called sublimate.
  2. A liquid condensed from vapour in distillation is called distillate.
  3. The liquid produced after filtering a suspension of a solid in a liquid is called filtrate.
  4. Supernatant liquid is the upper layer of fluid found after a mixture has been centrifuged.
  5. If there is a heterogeneous mixture containing an insoluble solid in a liquid, then the solid substance that settle down is called sediment.

Solution 26:
We use fractional distillation to separate alcohol from a mixture of alcohol and water since the difference in boiling point between alcohol and mixture is very less.

Solution 27:

  1. We obtain pure water from sea water by distillation.
  2. A sample of pure iodine and sodium chloride is obtained by sublimation.

Solution 28:
The separation of the mixture depends upon-

  1. Size of the constituents
  2. Magnetic properties of constituents
  3. Mass of the constituents
  4. Solubility of the constituents
  5. Miscibilities of the constituents
  6. Boiling point of the constituents
  7. Diffusion rate of the constituents

Solution 29:
This is a separation technique of solid-solid mixture. This method involves the use of a solvent in which only one of the solid present in the mixture dissolves. Undissolved solid is removed by filtration. Mixture of ammonium chloride and silver chloride is separated by this method.

Solution 30:

  1. By distillation and fractional distillation we separate the mixture of two liquids.
  2. Yes, mixture of chloroform (B.P.= 61 oC) and carbon tetrachloride (B.P.=77 oC) be satisfactorily separated by the process of fractional distillation which is used for separating the various fractions of petroleum.
    For this purpose we will make two fractionating columns in the apparatus.

Solution 31:

  1. Solid-solid mixtures
    1. Magnetic separation method-Separation of iron ore from impurities
    2. Gravity separation-Mixture of saw dust and sand
    3. Solvent extraction-Mixture of sulphur and sand
  2. Solid- liquid mixtures
    1. Evaporation-Water and sodium chloride
    2. Distillation-Iodine in chloroform
    3. Filtration-Barium sulphate in water
  3. Liquid-liquid mixtures
    1. By separating funnel-Oil and water mixture
    2. Distillation-Acetone and water
    3. Fractional distillation-Ethyl alcohol and water

Solution 32:
The chromatography is the technique of separating pure substances from the mixtures. The chromatographic techniques was first employed by a Russian scientist Michael Tswett in 1903 for the separation of coloured substance from the mixture.
Principle of chromatography: The principle of chromatography is based on the difference in the extent of interaction (absorption) of various substances with a stationary phase and a mobile phase. A substance which interacts strongly with the mobile phase goes ahead of the other substance which interacts strongly with the stationary phase.

Solution 33:
Ink generally contain more than one dye. This mixture of ink is used as moving phase. Different constituents of ink move at different speed. The solvent rises up the filter paper over the spot and carries the different coloured components of ink to different heights on the filter paper. Each spot thus obtained at a particular height on the filter paper contains a particular constituent of the ink. Thus, the components of the ink are separated.

Solution 34:
By the help of fractional distillation we separate the components of liquid air.

Solution 35:

  1. Increase in weight – Sulphuric acid and iron
  2. Decrease in weight – Sodium carbonate crystals
  3. No change in weight – Sodium chloride

Solution 36:
By filtration, we will separate a mixture of chalk powder and water.

Solution 37:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 6

Solution 38:
Fractionating column avoid the collection of distillate and re-distillation of distillate several times during fractional distillation.

Solution 39:
Two pair of liquids which can be separated by using a separating funnel-

  1. Oil and water
  2. Chloroform and water

Solution 40:
At first, with the help of magnet, iron nails will separate. Then, by sublimation camphor will separate from common salt.

Solution 41:
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 7
Frank ICSE Solutions for Class 9 Chemistry - Elements, Compounds and Mixtures 8

PAGE NO :44
Solution 42:

  1. When a magnet is moved over ‘X’, iron fillings are pulled away and stick to the magnet. When a magnet is moved over ‘Y’, it remained  unaffected.
  2. When’X’ is treated with carbon disulphide, sulphur dissolves but not iron. While, when’Y’ is treated with carbon disulphide, iron sulphide does not dissolve  but sinks to the bottom of the test tube.
  3. When ‘X’ is treated with dilute HCl, a colourless, odourless gas hydrogen is evolved which burns with a blue flame and is extinguished with a pop sound. While, when ‘Y’ is treated with dilute HCl, a colourless gas with the smell of rotten eggs is evolved which is H2S.
    There is difference in the behavior of ‘X’ and ‘Y’ because ‘X’ is a mixture while ‘Y’ is a compound. The component of a mixture do not react chemically, so retain their identity in the mixture while the components of compound react chemically, so do not retain their identity in the compound.

Solution 43:
Centrifugation is used in milk dairies to separate cream from milk dairies.

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Frank ICSE Solutions for Class 9 Chemistry – The Language of Chemistry

Frank ICSE Solutions for Class 9 Chemistry – The Language of Chemistry

PAGE NO :56
Solution 1:
Symbol – It is the short form or abbreviation used for the name of an element. It represents one atom of that element.
Formula – Formula of a compound represents the composition of a molecule of the substance in terms of the symbols of the elements present in the molecule.

Solution 2:

  1. CaCO3
  2. MgSO4
  3. Fe2 (SO4)3
  4. CaHCO3
  5. CuI
  6. K2Cr2O7
  7. KMnO4
  8. Na2SO4
  9. Mg (NO3)2
  10. Ca3 (PO4)2

Solution 3:

  1. Valency – The combining capacity of an element is called its valency.
  2. Helium < Sodium < Magnesium < Carbon < Phosphorous

Solution 4:
Law of conservation of matter governs a completely balanced equation. It states that “matter can neither be created nor destroyed.”

Solution 5:
A symbol signifies one atom of that element.

Solution 6:
Latin names of the following compounds are-
Iron                      –   Ferrum
Tin                        –   Stannum
Lead                     –   Plumbum
Sodium                –   Natrium
Potassium           –   Kalium
Mercury              –   Hydragyrum

Solution 7:
The equation in which the total number of atoms of each element in the reactants, on the left side of the equation is same as the number of atoms in the products formed, on the right side of the equation is called as balanced chemical equation.

Solution 8:
Frank ICSE Solutions for Class 9 Chemistry - The Language of Chemistry 1

Solution 9:
A chemical equation gives information about-

  1. What substances enter into a given reaction (reactants) and what products are formed as a result of the reaction.
  2. The  quantities of the reactants and the product formed.
  3. The  optimum conditions of temperature and pressure.

Solution 10:
Frank ICSE Solutions for Class 9 Chemistry - The Language of Chemistry 2

Solution 11:
H2 means hydrogen, O4 means oxygen and S means sulphur  in the formula of H2SO4.

Solution 12:

  1. The highest valency of the element Z is six.
  2. The formula of the fluoride of Z will be ZF6.

Solution 13:
The three valencies of element are-

  1. Two-Since the element X combines with two hydrogen to form H2X and two atoms of X combines with one carbon to form CX2.
  2. Four-Since the element X combines with two oxygen to form XO2.
  3. Six-Since the element X combines with three oxygen to form XO3.

Solution 14:
Variable valency – Some elements are capable of showing more than one valency in their compounds called variable valency.
Some elements show variable valency i.e. more than one valency since these elements have more than one common valency state.

Solution 15:
Chemical formula – It represents the composition of a molecule of the substance in terms of the symbols of the elements present in the molecule. The rule for writing the formula is criss-cross method.

  1. The positive and negative radicals are represented by their symbols and written side by side with the correct valency written below each.
  2. The valencies are divided by their highest common factor if any to get the simplest ratio.
  3. These numbers are then interchanged and written as subscripts.

Solution 16:
Frank ICSE Solutions for Class 9 Chemistry - The Language of Chemistry 3

Solution 17:

  1. Sodium hydrogencarbonate
  2. Sodium hexacyanoferrate(III)
  3. Manganese(II) borate
  4. Calcium phosphate
  5. Potassium manganate(VI)

Solution 18:
Co stands for cobalt which is an element while CO stands for carbon monoxide which is a compound.

Solution 19:
Radical – A radical is an atom or a group of atoms of same or different elements that behaves in the manner of positive or negative ion. Radicals have their own combining power(valency) and chemical formulae.
Examples-
Monovalent  radicals -H,OH,Cl,NO3,H+,Na+,K+,NH4+
Trivalent radicals-PO43- ,Fe(CN)63-,AsO3 3-,N3-,Fe3+,Al3+,Bi3+,Au3+

Solution 20:
Frank ICSE Solutions for Class 9 Chemistry - The Language of Chemistry 4

Solution 21:

  1. Anion – Negatively charged radicals are termed as anions.
  2. Cation – Positively charged radicals are termed as cations.

Solution 22:
Disadvantages associated with hit and trial method of balancing of equations-

  1. It is tedious and takes a long time.
  2. The method is rather difficult for balancing such equations which contain the same element being repeated in a number of compounds.
  3. It does not give any information regarding the mechanism of the reaction.

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Frank ICSE Solutions for Class 10 Chemistry – Study Of Acids, Bases and Salts

Frank ICSE Solutions for Class 10 Chemistry – Study Of Acids, Bases and Salts

PAGE NO : 62
Solution 1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 1

Solution 2:

  1. (i) Hydrogen chloride HCl
    (ii) Nitric acid HNO3
  2. (i) Carbonic acid H2CO3
    (ii) Oxalic acid (COOH)2
  3. (i) Sulphuric acid H2SO4
    (ii) Hydrogen chloride HCl
  4. (i) Carbonic acid H2CO3
    (ii) Acetic acid

Solution 3:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 2

Solution 4:

  1. The pH of a solution is defined as the negative logarithm (base 10) of the hydronium ion concentration present in the solution.
    pH =-log10 [H3O+]
  2. The three applications of pH scale are:
    • It is used to determine the acidic or basic nature of the solution.
    • It is used to determine hydronium ion concentration present in the solution.
    • It is used to find out neutrality of the solution.

Solution 5:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 3

Solution 6:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 4

Solution 7:

  1. Base in solution furnishes the ions:
    Hydroxide ion/ oxide ion and a metallic ion.
  2. A weak alkali furnishes the ions:
    Hydroxide ion and metallic ion and molecules of weak alkali./
  3. An acid in a solution furnishes the ions:
    Hydronium / Hydrogen ion and a negative ion.

Solution 8:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 5

PAGE NO : 63
Solution 9:

  1. CaO
  2. NaOH
  3. CuO
  4. Cu[(OH)2]
  5. H2CO3
  6. Ferric hydroxide [Fe (OH)3].
  7. CuO
  8. NH3

Solution 10:
Anhydrous hydrogen chloride is not an acid but its aqueous solution is a strong acid because anhydrous means without water and we know that the property of acidity is shown by a substance only when it is dissolved in water or its aqueous solution is prepared.

Solution 11:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 6

Solution 12:
Strength of an acid measures the ease with which the acid can ionize to produce hydrogen or hydronium ions when dissolved in water. Those acids which can easily ionize to form hydrogen ions are called strong acids while those which can partially ionize to form hydrogen ions are called weak acids.
Strength of an acid depends upon many factors such as:

  1. Molecular structure of the acid
  2. The temperature
  3. Properties of the solvent

Solution 13:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 7

Solution 14:
Solution B with pH value 9 will give pink colour with phenolphthalein.
Concept Insight: Bases give pink colour with phenolphthalein because a base will abstract two protons from phenolphthalein and the resulting phenolphthalein ion provides pink colour to the solution.

Solution 15:
Two indicators for identification of acid are methyl red and Thymol blue.

Solution 16:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 8

Solution 17:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 9

Solution 18:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 10

Solution 19:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 11

Solution 20:

  1. Efflorescence: It is the phenomenon by which hydrated salts on exposure to dry air, lose their water of crystallization and crumble to powder.
  2. Hygroscopy: It is the phenomenon by which substances absorb moisture from air, but only sufficiently so as to become wet.
  3. Water of crystallization: It is the fixed amount of water that is present in a crystal as an integral part of its constitution. Hydrated salts are salts having water of crystallisation.

Solution 21:
Deliquescence is the phenomenon by which certain salts absorb moisture from air, lose their water of crystallization and dissolve in it to form a saturated solution.
The substances which exhibit deliquescence are called deliquescent.
For example Caustic soda NaOH, Caustic potash KOH.

Solution 22:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 12

Solution 23:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 13

Solution 24:

  1. Common salt gets wet during rainy season because the commercially available salt contains impurities, like magnesium chloride, which are deliquescent substances. These absorb moisture from atmosphere and make the table salt wet.
  2. (i)  Na2CO4.10H2O = Washing soda
    (ii) MgSO4.7H2O = Epsom salt
    (iii)CuSO4.5H2O = Blue vitriol
    (iv) ZnSO4.7H2O = White vitriol

PAGE NO : 64
Solution 1996-1:

  1. pH of a solution having pH 7 can be increased by adding a base to it such as NaOH.
  2. pH can be decreased by adding an acid such as HCl to it.
    If a solution changes colour of litmus from red to blue, it shows that its pH is above 7.

Solution 1996-2:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 14

Solution 1996-3:

  1. Zinc sulphate = Zinc and dilute sulphuric acid
  2. Copper sulphate = Copper oxide and dilute sulphuric acid
  3. Sodium sulphate = Sodium carbonate solution and dilute sulphuric acid
  4. Lead sulphate = Lead carbonate and dilute sulphuric acid

Solution 1997-1:
The term acid salt means the salt formed by partial replacement of the hydrogens present in the acid by metallic or ammonium ions.
For example: NaHCO3

Solution 1997-2

  1. pH scale is used to express the acidic or basic nature of solution.
  2. pH of pure water is 7 since it does not have any impurities.
  3. (a) A soluble oxide of A will have pH less than the pH of pure water i.e. below 7.
    (b) A solution of ‘B’ will have more pH than pure water i.e. above 7.

Solution 1997-3:

  1. Water of crystallization: It is the fixed amount of water that is present in a crystal as an integral pat of its constitution. Compounds having water of crystallization are called hydrous salts.
    For example: Sodium carbonate Na2CO3 has 10 molecules of water present as water of crystallization Na2CO3.10H2O
  2. Anhydrous: Hydrous salt on heating lose their water of crystallization, such salts are then called anhydrous.
    For example:Na2CO3.10H2O on losing 10 molecules of water forms Na2CO3

Solution 1997-4:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 15

Solution 1998-1:

  1. Water of cystallization.
  2. White.
  3. Efflorescence.
  4. Sodium chloride.

Solution 1998-2:
Those acids which ionize partially in aqueous solution and thus they contain ions as well as molecules of the acid. Organic acid such as CH3COOH, is a weak acid.

Solution 1998-3:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 16

PAGE NO : 65
Solution 1998-4:
The name and formula of the acid salt which gives sodium ions and sulphate ions in solution is Sodium hydrogen sulphate NaHSO4

Solution 1999-1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 17

Solution 2000-1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 18

Solution 2001-1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 19

PAGE NO : 66
Solution 2002-1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 20

Solution 2003-1:

  1. Hydronium, positive.
  2. Acid, metal.

Solution 2003-2:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 21

Solution 2004-1:
methods for preparation:

  1. Preparation of copper(II) chloride.
    Action of an acid on an oxide or carbonate
  2. Preparation of iron(III) chloride.
    Direct combination
  3. Preparation of iron (II) chloride.
    Action of an acid on a metal
  4. Preparation of lead (ii) chloride
    Precipitation (double decomposition)
  5. Preparation of sodium chloride
    Neutralization of an alkali by an acid.

Solution 2005-1:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 22

PAGE NO : 67
Solution 2005-2:
Positive, hydroxyl, Salt, Neutralization.

Solution 2005-3:
When neutral litmus solution is added to sodium hydrogen carbonate solution, litmus solution turns red

Solution 2006-1:

  1. From pink to colourless.
  2. From orange to pink.
  3. From colourless to red.

Solution 2007-1:

  1. Hydronium
  2. Hydroxide
  3. Salt
  4. Water
  5. Hydrogen

Solution 2007-2:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 23

Solution 2008-1:

  1. Complex salt.
  2. Alkali.

Solution 2009-1:
Acidified potassium dichromate paper

PAGE NO : 68
Solution 2009-2:

  1. Solution B.
  2. Solution A.
  3. Solution B
  4. Solution of ammonium hydroxide NH4OH is a weak alkali.

Solution 2009-3:
Frank ICSE Solutions for Class 10 Chemistry - Study Of Acids, Bases and Salts 24

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Frank ICSE Solutions for Class 9 Chemistry – Physical and chemical changes

Frank ICSE Solutions for Class 9 Chemistry – Physical and chemical changes

PAGE NO :74
Solution 1:
A physical change is a temporary change in which no new substance is formed and the composition or identity of the substance is not altered although certain specific physical properties may be changed.

Solution 2:
A chemical change is a permanent change in which the original substance gives rise to one or more substances with different properties.

Solution 3:
The reactions in which heat is evolved are called exothermic reactions while the reactions in which heat is absorbed are called endothermic reactions.

Solution 4:

  1. False
  2. False
  3. False
  4. False
  5. True

Solution 5:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 1

Solution 6:
Possible conditions for a chemical change are-

  1. One or more new substance is formed during reaction.
  2. The change occurring during the reaction is permanent.
  3. The mass of the substance undergoing a chemical change is generally altered.
  4. Chemical change involves  making and breaking of bond.

Solution 7:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 2

Solution 8:

(a) Redox reaction – The reaction in which both oxidation and reduction takes place simultaneously is known as rtedox reaction. Oxidation is a reaction that involves the addition of oxygen or the removal of the hydrogen. Reduction is a reaction that involves the addition of hydrogen or the removal of oxygen.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 3
(b) Oxidation – Oxidation is a reaction that involves the addition of oxygen or the removal of the hydrogen. In electronic concept, it is defined as the process in which an atom, molecule or ion loses one or more electrons. This results in increase in the positive charge or decrease in negative charge on the resulting species.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 4
(c) Reduction – Reduction is a reaction that involves the addition of hydrogen or the removal of oxygen. In the electronic concept, it is defined as the process in which an atom, molecule or ion gains one or more electrons. This results in increase in the negative  charge or decrease in positive charge on the resulting species.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 5

Solution 9:

  1. Exothermic reaction
  2. Endothermic reaction

Solution 10:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 6

Solution 11:
The chemical reactions which occur with the absorption of light energy are called photochemical reactions.
Examples-
Decomposition of silver nitrate takes place in the presence of light.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 7

Solution 12:
As the burning substance combines with oxygen ,the total mass of the products should be greater than that of the burning substance. For example,when,magnesium is burnt,a new substance magnesium oxide is formed,whose weight is greater than that of the original magnesium.
Experiment – A crucible is weighed containing about 0.5 gm of magnesium.Now crucible is heated.When magnesium begins to burn,the lid is put back on the crucible and the lid is occasionally raised to allow air to enter and burn the magnesium such that no product is lost.When,all the magnesium has been burnt up, the crucible is allowed to cool and then on weighing it  we observe that there is gain in weight.

Solution 13:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 8

Solution 14:
Three conditions necessary for burning are-

  1. The substance to be burnt must be combustible.
  2. A supporter of combustion such as air or oxygen must be present.
  3. A combustible substance must be heated to its ignition temperature.

PAGE NO :75
Solution 15:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 9

Solution 16:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 10

Solution 17:
When oxidation occurs there is a loss of electrons but simultaneously there is a gain of electrons by other species which is called reduction. These both process occur simultaneously so we can say that both oxidation and reduction go hand in hand and such reactions are known as redox reaction.

Solution 18:

  1. Copper is oxidized to copper sulphate while sulphur in sulphuric acid is reduced to sulphur dioxide.
  2. Silver in silver oxide is reduced to silver while oxygen in hydrogen peroxide is oxidised to molecular oxygen.

Solution 19:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 11
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 12

Solution 20:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 13

Solution 21:
A candle is a stick of paraffin wax with cotton wick.As a candle burns wax melts and trickles down. It gets solidified shortly. This is physical change. Paraffin wax is a mixture of hydrocarbons. When wick catches fire, paraffin wax melts, evaporates and burns in air like any hydrocarbon to give carbon dioxide and water. This is a chemical change.

Solution 22:

  1. physical
  2. chemical
  3. chemical
  4. physical

Solution 23:
Two examples are:-

  1. Burning of wood-carbon get oxidized and oxygen gets reduced.
  2. Rusting-In it iron is oxidized.

Solution 24:

  1. Chromium(VI) .
  2. Hydrogen peroxide
  3. Barium carbonate.
  4. Silver nitrate.
  5. Manganese dioxide.

Solution 25:
Ignition temperature –
Ignition temperature is the lowest temperature up to which temperature of a substance must be raised so that it catches fire.
A combustible substance must be heated to its ignition temperature for burning.

Solution 26:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 14

Solution 27:
On heating few crystals of iodine in a test tube, the grey crystals sublimes and dense violet fumes are seen. On cooling, the vapours again form the crystals. So, a physical change can be reversed.

Solution 28:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 20

Solution 29:
When water is freezed and evaporated, these both are physical changes because-

  1. The change is temporary and reversible.
  2. No new substance is formed and the chemical composition of the original substance remains the same.
  3. Mass of the substance remains unchanged
  4. The amount of energy required to bring about a physical change is generally equal to the amount of energy required to reverse the change. Hence,there is no net energy change involved.

Solution 30:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 15

Solution 31:
Air is necessary for burning. Incorrect amount of air in fuel combustion accounts for the largest losses in combustion system. If the fuel does not get enough air for combustion it will generate smoke and a potentially unhealthy mixture of gas products.

Solution 32:

  1. (a) Combustible substances -The substances that catch fire and burn easily. Ex-Wood, Charcoal, petrol, kerosene etc.
    Non-combustible substances-Substance which cannot burn in air or oxygen are called as non- combustible substances. Ex-Nitrogen gas, carbon dioxide etc.
  2. (b) Two substances other than oxygen that support combustion are-
    1. Hydrogen
    2. Nitrogen

Solution 33:

  1. (a)
    1. Burning of coal in air releases CO2 in air.
    2. Respiration releases carbon dioxide and water vapours.
  2. (b)
    1. Photosynthesis removes CO2 from the atmosphere. Plants take carbon dioxide from the atmosphere in the presence of sunlight and use it to synthesise glucose with the liberation of oxygen.
    2. Some man made chemical activities such as setting of mortar also use atmospheric carbon dioxide and helps in removing carbon dioxide.

Solution 34:
Nitrogen is inert in nature and does not support combustion while oxygen supports combustion.If proportions of nitrogen and oxygen in the air were reversed then the rate of combustion of substances will increase.

Solution 35:
Heating of sulphur – If some powdered sulphur is heated gently in a glass test tube, it melts to a pale yellow liquid. Flame is removed to stop heating, it is quickly changed back to solid sulphur.

PAGE NO :76
Solution 36:
Activity series –
The arrangement of the metals in the decreasing order of their chemical reactivity is called the activity series.
In displacement reactions, a more reactive element (metal or non-metal) displaces a lesser reactive element from its compound. With the help of the activity series, it is possible to predict which metals will displace other metals from their solutions.

Solution 37:
Balance of oxygen and carbon dioxide is maintained in nature because there is a natural oxygen cycle and a natural carbon cycle operating all the time by which the desired proportions of the two gases in the air are maintained. This is also known as carbon dioxide-oxygen cycle.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 16

Solution 38:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 17

Solution 39:
Carbon dioxide from the atmosphere enters the plant through photosynthesis, where carbohydrates are produced. From green plants, the carbon in the form of carbohydrates, etc. enter the animal and human bodies. The atmospheric carbon dioxide gets dissolved in oceans by diffusion. Marine algae and photosynthetic bacteria obtain carbon dioxide from water.
Carbon dioxide returns to the atmosphere by respiration, combustion of fossil fuels like coal, wood, petroleum etc., weathering of rocks, volcanic eruptions etc.
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 18

Solution 40:
Frank ICSE Solutions for Class 9 Chemistry - Physical and chemical changes 18

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