Solved Sample Paper 5

Section A

Question 1(i)

Which of the following pairs of metals are extracted only by electrolysis?

1. Na, Pb
2. Ca, Cu
3. Na, Mg
4. Ag, K

Answer

Na, Mg

Reason — Metals which are higher in the electrochemical series such as potassium, calcium, sodium, magnesium and aluminium are extracted by electrolysis.

Question 1(ii)

The particles present in strong electrolytes are

1. only molecules
2. mainly ions
3. ions and molecules
4. only atoms

Answer

mainly ions

Reason — Strong electrolytes dissociate almost completely, hence, they consist of mainly ions.

Question 1(iii)

In the following reaction, alkaline KMnO₄ adds oxygen to the ethanol and converts ethanol to an acid.

CH₃CH₂OH $\xrightarrow{\text{KMnO}_4}$ CH₃COOH

Which of the following is correct?

P. Alkaline KMnO₄ acts as reducing agent.

Q. Alkaline KMnO₄ acts as an oxidising agent.

1. Only P
2. Only Q
3. Both P and Q
4. Neither P nor Q

Answer

Only Q

Reason — Alkaline KMnO₄ acts as an oxidising agent as it oxidises ethanol (alcohol) to form ethanoic acid (an acid).

Question 1(iv)

On reaction of magnesium nitride with water, the gas which is liberated is ...............

1. NH₃
2. HCl
3. H₂
4. N₂

Answer

NH₃

Reason — Reaction of magnesium nitride with water liberates ammonia gas. The reaction is:

Mg₃N₂ + H₂O ⟶ MgO + NH₃

Question 1(v)

In an exothermic process, energy is released in the form of heat or light.

Which of the following could be exothermic processes?

P. Sublimation of camphor crystals

Q. Reaction of water with quick lime

R. Dilution of an acid

1. Only P
2. Only Q
3. Only R
4. Both Q and R

Answer

Both Q and R

Reason — Reaction of water with quick lime and Dilution of an acid, both are exothermic processes. Sublimation of camphor crystals is an endothermic process.

Question 1(vi)

Percentage of calcium in calcium carbonate (CaCO₃) is

1. 40
2. 30
3. 48
4. 36

Answer

40

Reason —

Molecular weight of CaCO₃
= 40 + 12 + (16 x 3)
= 40 + 12 + 48
= 100 g

100 g of CaCO₃ contains 40 g of calcium

Therefore, percentage of Ca = $\dfrac{40}{100}$ x 100 = 40%

Question 1(vii)

The pH values of four solutions A, B, C and D are given in the table.

Which solution will liberate CO₂ when reacted with sodium carbonate?

1. A
2. B
3. C
4. D

Answer

B

Reason — Solution B is the only acidic solution in the list. Acids liberate CO₂ gas when treated with carbonates. Hence, solution B will liberate CO₂ when reacted with sodium carbonate.

Question 1(viii)

Name the gas produced when ammonium sulphate is heated with sodium hydroxide solution.

1. Hydrogen chloride gas
2. Ammonia
3. Sulphuric acid
4. Chlorine

Answer

Ammonia

Reason — Ammonia gas is obtained by warming ammonium sulphate with sodium hydroxide solution.

(NH₄)₂SO₄ + 2NaOH ⟶ Na₂SO₄ + 2H₂O + 2NH₃

Question 1(ix)

In which of the following beaker (I, II, III and IV) will coating on Zn be done?

1. I and III
2. II only
3. III and IV
4. IV only

Answer

I and III

Reason — As zinc is more reactive than copper and iron so it displaces copper and iron from their solution. Hence, iron and copper will form coating on zinc due to displacement reaction.

Question 1(x)

The vapour density of carbon dioxide (C = 12 and O = 16) is ...............

1. 32
2. 16
3. 44
4. 22

Answer

22

Reason — Molecular weight of carbon dioxide = 12 + 2(16) = 12 + 32 = 44 g

Vapour density of gas =

$\dfrac{\text{Molecular weight}}{2} \\[0.5em] = \dfrac{44}{2} \\[0.5em] = 22 \text{ g}$

Hence, vapour density of carbon dioxide is 22 g

Question 1(xi)

The volume occupied by 1 mole of gas at STP is ...............

1. 2.42 L
2. 2.24 L
3. 2.44 L
4. 22.4 L

Answer

22.4 L

Reason — The volume occupied by 1 mole of gas at STP is 22.4 L

Question 1(xii)

An amphoteric hydroxide having gelatinous white precipitate is ...............

1. zinc hydroxide
2. sodium hydroxide
3. copper (II) hydroxide
4. None of the above

Answer

zinc hydroxide

Reason — Zinc hydroxide is an amphoteric hydroxide having gelatinous white precipitate.

Question 1(xiii)

Among the given elements, one with least electronegativity is

1. lithium
2. carbon
3. boron
4. fluorine

Answer

Lithium

Reason — Electronegativity increases from left to right. As lithium is on the left side in periodic table hence it has the least electronegativity among the given options.

Question 1(xiv)

A dry test tube containing lead nitrate is heated. Which of the following would be observed?

P. Brown fumes are given out.

Q. White coloured residue with yellow fumes are seen.

R. Yellow coloured residue is seen.

1. Only P
2. Only Q
3. Only R and Q
4. Both P and R

Answer

Both P and R

Reason — On heating, lead nitrate decomposes to form yellow coloured lead oxide, brown coloured fumes of nitrogen dioxide and oxygen as per the below reaction:

2Pb(NO₃)₂ (s) $\xrightarrow{\Delta}$ 2PbO (s) + 4NO₂ ↑ + O₂ ↑

Question 1(xv)

The energy required to remove an electron from a neutral isolated gaseous atom is called

1. Ionisation Potential
2. Electronegativity
3. Electron Affinity
4. Valency

Answer

Ionisation Potential

Reason — Ionisation Potential is the energy required to remove an electron from a neutral isolated gaseous atom and convert it into a positively charged gaseous ion.

Question 2(i)

Complete the following by choosing the correct answer from the bracket.

(a) The number of electrons present in valence shell of a halogen is ............... (5/7).

(b) The degree of ionisation of an acid in an aqueous solution is called its ...............(strength/concentration)

(c) Pure nitric acid decomposes to give yellow solution on exposure to heat due to the formation of ............... (nitrogen dioxide/nitrogen trioxide)

(d) Hydrocarbon having triple bond is called ............... (alkene/alkynes)

(e) The commonly used catalyst for the conversion of ethene to ethane is ............... (nickel/iron).

Answer

(a) The number of electrons present in valence shell of a halogen is 7.

(b) The degree of ionisation of an acid in an aqueous solution is called its strength.

(c) Pure nitric acid decomposes to give yellow solution on exposure to heat due to the formation of nitrogen dioxide.

(d) Hydrocarbon having triple bond is called alkynes.

(e) The commonly used catalyst for the conversion of ethene to ethane is nickel.

Question 2(ii)

Match the following Column I with Column II

Answer

Question 2(iii)

Identify the following.

(a) The catalyst that is used during the oxidation of SO₂.

(b) The formula which shows the arrangement of atoms in the molecule of a compound.

(c) The amount of energy released while converting a neutral gaseous isolated atom into a negatively charged gaseous ion by the addition of electron.

(d) An acid which is formed by the oxidation of ethyne by alk. KMnO₄.

(e) The process of heating the concentrated ore in the absence or limited supply of air at a temperature not sufficient to melt the ore.

Answer

(a) Vanadium pentoxide V₂O₅.

(b) Molecular formula

(c) Electron affinity

(d) Oxalic acid

(e) Calcination

Question 2(iv)

The diagram shows an experiment set up for the laboratory preparation. Study the diagram and answer the following.

(a) Name the experiment illustrated above.

(b) Identify the gas Y and which property of gas Y, does this experiment demonstrate?

(c) State the colour of the water that has entered in the round bottom flask and name another gas which has the same property which can be demonstrated by this experiment.

Answer

(a) Fountain Experiment.

(b) The gas Y is hydrogen chloride. The high solubility of hydrogen chloride gas in water is demonstrated by the fountain experiment.

(c) Red colour fountain can be seen in the round bottom flask. Ammonia gas is also highly soluble in water and this can be demonstrated with the help of fountain experiment.

Question 2(v)

(a) Give the chemical names and formula of main ores of

1. aluminium
2. iron
3. zinc

(b) Write the principle metal(s) of the following alloys.

1. Brass
2. Stainless steel

Answer

(a) The chemical names and formula of main ores are given below:

(b) The principle metal(s) of the given alloys are:

1. Copper and Zinc.
2. Iron and Chromium.

Section B

Question 3(i)

Distinguish between the following as directed.

(a) Ethene and ethyne (on the basis of preparation)

(b) Sodium carbonate and sodium sulphite (using dilute hydrochloric acid)

Answer

(a) Ethene is prepared in laboratory by dehydration of ethyl alcohol using sulphuric acid:

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

Ethyne is prepared in laboratory by the reaction of calcium carbide and water:

$\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \underset{\text{Calcium Hydroxide}}{\text{Ca(OH)}_2}$

(b) When Sodium carbonate is treated with dil. HCl, odourless carbon dioxide gas is produced.

Na₂CO₃ + 2HCl ⟶ 2NaCl + H₂O + CO₂ ↑

However, when sodium sulphite is treated with dil.HCl, sulphur dioxide gas with a suffocating odour (burning smell) is produced.

Na₂SO₃ + 2HCl ⟶ 2NaCl + H₂O + SO₂ ↑

Question 3(ii)

Draw the electron dot structure for the following.

(a) NaCl

(b) MgCl₂

Answer

(a) NaCl

(b) MgCl₂

Question 3(iii)

An element X has atomic number 35. Answer the following questions.

(a) State the period and group to which it belongs.

(b) It is a metal or non-metal?

(c) Write a formula between X and hydrogen.

Answer

(a) The element belongs to group 17 and period 4.
Reason — The element X has atomic number 35 and so the electronic configuration will be 2, 8, 18, 7. The number of shells present in an atom determines it's period. Hence, Z will belong to 4th period as it has four shells. The number of valence electrons determines the group and as 7 electrons are present in valence shell hence the element will be in group 17.

(b) It is a non-metal.

(c) HX

Step 1 — Write each symbol with its valency

$\text{H}^{1+} \phantom{\nearrow} \text{X}^{1-}$

Step 2 — Interchange the valencies

$\overset{\phantom{2}{1}}{\text{H}} \space {\searrow}\mathllap{\swarrow} \space \overset{1}{\text{X}} \Rightarrow \underset{\phantom{1}{1}}{\text{H}} \space {\searrow}\mathllap{\swarrow} \space \underset{1}{\text{X}} \\[0.5em]$

Step 3 — Write the interchanged number, ignore equal numbers & hence the formula is : $\bold{HX}$

Question 3(iv)

Choose the substances given below to answer the following questions.

Ferrous chloride

Iron (II) sulphate

Iron (II) chloride

Copper chloride

Aluminium oxide

Copper (II) oxide

(a) A chloride which forms a precipitate that is soluble in excess of ammonium hydroxide.

(b) The salt which gives a dirty green precipitate with sodium hydroxide solution.

(c) The metal oxide which can react with acid as well as alkali.

Answer

(a) Copper chloride.

(b) Iron (II) sulphate

(c) Aluminium oxide

Question 4(i)

Identify the acid and write the balanced equation for the following.

The acid on mixing with silver nitrate solution produces a white precipitate which is soluble in excess ammonium hydroxide and nitric acid.

Answer

Dilute hydrochloric acid

AgNO₃ + HCl ⟶ AgCl (white ppt.) + HNO₃

AgCl + 2NH₄OH ⟶ 2H₂O + [Ag(NH₃)₂]Cl

Question 4(ii)

Name a probable cation present based on the following observation.

(a) White precipitate insoluble in NH₄OH but soluble in NaOH.

(b) NaOH solution when added to the solution (A) gives a reddish brown precipitate.

Answer

(a) Pb²⁺

(b) Fe³⁺

Question 4(iii)

State one relevant observation for each of the the following reactions.

(a) When hydrogen chloride gas is passed through a solution of sodium thiosulphate.

(b) Concentrated sulphuric acid is added to a solution of potassium nitrate.

(c) When fused lead bromide is electrolysed.

Answer

(a) When hydrogen chloride gas is passed through a solution of sodium thiosulphate a yellow precipitate of Sulphur can be seen along with water, Sodium chloride, and Sulphur dioxide gas which has a burning smell.

Na₂S₂O₃ + 2HCl ⟶ 2NaCl + H₂O + SO₂ + S ↓

(b) Nitric acid is released with a pungent odour when concentrated sulphuric acid is added to a solution of potassium nitrate.

KNO₃ + H₂SO₄ (conc.) $\xrightarrow{\lt 200 \degree\text{C}}$ KHSO₄ + HNO₃

(c) At anode, reddish brown fumes of bromine vapours are seen. At cathode, silver grey deposit of lead metal is observed.
At cathode:
Pb²⁺ + 2e^- ⟶ Pb
At anode:
Br^- ⟶ Br + e^-

Question 4(iv)

Give balanced chemical equations for the following.

(a) Calcium bicarbonate reacts with dilute hydrochloric acid.

(b) Ferric hydroxide with nitric acid.

(c) Zinc nitrate with ammonium hydroxide

Answer

(a) Ca(HCO₃)₂ + 2HCl ⟶ CaCl₂ + 2H₂O + 2CO₂

(b) Fe(OH)₃ + 3HNO₃ [dil.] ⟶ Fe(NO₃)₃ + 3H₂O

(c) Zn(NO₃)₂ + 2NH₄OH ⟶ 2NH₄NO₃ + Zn(OH)₂

Question 5(i)

The following questions relate to mole concept.

(a) the volume of 320 g of SO₂ at STP.

(Atomic mass of S = 32 and O = 16)

(b) the mass of 10²² atoms of sulphur.

[Atomic mass : S = 32 and O = 16, Avogadro's number (N_A) = 6.022 x 10²³]

Answer

Gram molecular mass of SO₂ = 32 + 2(16) = 32 + 32 = 64 g

64 g of SO₂ occupy 22.4 lit of vol at STP

∴ 320 g of SO₂ will occupy = $\dfrac{22.4}{64}$ x 320 = 112 lit.

Hence, volume of 320 g of SO₂ = 112 lit.

(b) Gram molecular mass of S = 32

6.022 × 10²³ atoms weigh = 32 g

10²² atoms will weigh = $\dfrac{32}{6.022 \times 10^{23}}$ x 10²² = 0.531 g

Hence, the mass of 10²² atoms of sulphur = 0.531 g

Question 5(ii)

For each of the substances given below, what is the role played in extraction of ZnO and Al respectively.

(a) Coke

(b) Cryolite

Answer

(a) Coke (C) is used as a reducing agent in the extraction of zinc from zinc oxide.

$\text{ZnO} + \text{C} \xrightarrow{\Delta} \text{Zn} + \text{CO} [\text{g}]$

(b) Addition of Cryolite during the extraction of Al lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.

Question 5(iii)

The following questions are pertaining to the laboratory preparation of hydrochloric acid.

(a) Name the reactants used during the laboratory preparation of hydrochloric acid.

(b) Give suitable reason for choosing the reactants for laboratory preparation.

(c) Write balanced chemical equation for the reaction taking place below 200°C.

Answer

(a) Sodium Chloride [NaCl] and Concentrated Sulphuric acid [H₂SO₄]

(b) Sodium chloride is preferred as it is cheap and easily available, whereas, conc. sulphuric acid is used as it is non-volatile and has a high boiling point hence it displaces the volatile HCl from the salt sodium chloride.

(c) NaCl + H₂SO₄ (conc.) $\xrightarrow{\lt 200 \degree\text{C}}$ NaHSO₄ + HCl

Question 5(iv)

Give reasons

(a) Liquid ammonia is used as a refrigerant in ice plants.

(b) Only all-glass apparatus should be used for the preparation of nitric acid by heating concentrated sulphuric acid and potassium nitrate.

(c) A piece of wood becomes black when concentrated sulphuric acid is poured on it.

Answer

(a) Liquid ammonia is a clear, colourless liquid under pressure. It evaporates rapidly and produces cooling effect. Moreover, Ammonia is environmentally compatible, has superior thermodynamic properties and its leaks are easily detectable due to its recognizable odour. All these reasons make liquid ammonia a good refrigerant.

(b) All glass apparatus is used in the laboratory preparation of nitric acid since the vapours of nitric acid being highly corrosive attack rubber, cork, etc.

(c) A piece of wood becomes black because of the dehydrating property of sulphuric acid. It readily removes elements of water from other compounds.
[C₆H₁₀O₅]n $\xrightarrow{\text{Conc. H}_2\text{SO}_4}$ 6[C]_n + 5[H₂O]_n

Question 6(i)

Name the functional group in the following organic compounds.

(a) CH₃COOH

(b) (H₃C)₃C-OH

(c) CH₃CH₂COOH

Answer

(a) Carboxylic acid [—COOH]

(b) Alcohol [—OH]

(c) Carboxylic acid [—COOH]

Question 6(ii)

(a) Write the cell reaction for the electrolysis of dil. AgNO₃ solution using Ag anode and Cu cathode.

(b) Name a compound of ammonia which sublimes on heating?

(c) Name the gas evolved on reaction of aluminium with boiling concentrated caustic alkali solution, write the equation.

Answer

(a) AgNO₃ ⇌ Ag⁺ + NO₃^-

H₂O ⇌ H⁺ + OH^-

Reaction at anode :
4OH^- - 4e^- ⟶ 4OH
4OH ⟶ 2H₂O + O₂ ↑

Reaction at cathode :
H⁺ + 1e^- ⟶ H
H + H ⟶ H₂ ↑

(b) Ammonium chloride

(c) Hydrogen gas is evolved

2Al + 2NaOH + 2H₂O ⟶ 2NaAlO₂ + 3H₂ ↑

Question 6(iii)

(a) A compound X having vinegar like smell when treated with ethanol in the presence of the acid, Z, gives a compound Y which has a fruity smell.

The reaction is

$\text{C}_2\text{H}_5\text{OH} + \text{X} \xrightarrow{\text{Z}} \text{Y} + \text{H}_2\text{O}$

1. Identify X, Y and Z.
2. Name the above reaction.

(b) Name the element in period 3 whose affinity is zero.

Answer

$\underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O}$

(a)

1. X, Y and Z are:
   • X → Acetic acid
   • Y → Ethyl acetate
   • Z → Concentrated Sulphuric acid
2. Esterification reaction

(b) Argon

Question 7(i)

If 6 L of hydrogen and 4 L of chlorine are mixed and exploded and if water is added to the gases formed, find the volume of the residual gas.

Answer

[By Lussac's law]

$\begin{matrix} \text{H}_2 & + & \text{Cl}_2 &\longrightarrow & 2\text{HCl} \\ 1 \text{ vol.} & : & 1 \text{ vol.} & \longrightarrow & 2\text{ vol.} \end{matrix}$

To calculate the amount of hydrogen used:

$\begin{matrix}\text{Cl}_2 & : & \text{H}_2 \\ 1 \text{ vol.} & : & 1 \text{ vol.} \\ 4 \text{ lit.} & : & \text{x} \end{matrix}$

$\therefore x = \dfrac{1}{1} \times 4 = 4 \text{ lit.}$

Remaining hydrogen = 6 - 4 = 2 lit.

To calculate the amount of HCl :

$\begin{matrix}\text{Cl}_2 & : & \text{HCl} \\ 1 \text{ vol.} & : & 2 \text{ vol.} \\ 4 \text{ lit.} & : & \text{x} \end{matrix}$

$\therefore x = \dfrac{2}{1} \times 4 = 8 \text{ lit.}$

Hence, after reaction 8 lit of HCl is formed which dissolves in water and 2 lit of hydrogen is left.

∴ 2 lits. of hydrogen is left.

Question 7(ii)

Define

(a) Relative molecular mass.

(b) Alkanes.

Answer

(a) The number of times one atom of an element is heavier than $\dfrac{1}{12}$ th the mass of an atom of carbon [C¹²] is known as the Relative Atomic Mass [RAM] of the element.

RAM = $\dfrac{\text{Mass of one atom of the element }}{\dfrac{1}{12} \text{th the mass of an atom of carbon }}$

(b) Saturated aliphatic hydrocarbons containing carbon-carbon single bond are known as alkanes. They are also known as paraffins and have the general formula as C_nH_2n+2

Question 7(iii)

Choose the role played by different solutions as A, B, C, which is responsible for the observation given in 1 to 3.

A. Solution X is a sodium hydroxide solution.

B. Solution Y is a weak acid.

C. Solution Z is dilute sulphuric acid.

(1) Liberate sulphur dioxide from sodium sulphite?

(2) Give a white precipitate with zinc sulphate solution?

(3) Contain solute molecules and ions?

Answer

(1) C. Solution Z is dilute sulphuric acid
Na₂SO₃ + H₂SO₄ ⟶ Na₂SO₄ + H₂O + SO₂ ↑

(2) A. Solution X is sodium hydroxide solution.
ZnSO₄ + 2NaOH ⟶ Zn(OH)₂ ↓ + Na₂SO₄

(3) B. Solution Y is a weak acid

Question 7(iv)

X[2, 8, 8, 1] and Y[2, 8, 18, 7] are two elements. Using this information complete the following:

(a) ............... is the metallic element.

(b) Formula of the molecule of Y is ...............

(c) ............... is bad conductor of electricity.

Answer

(a) X is the metallic element.
Reason — As X has one valence electron, hence it is a metal.

(b) Formula of the molecule of Y is Y₂.
Reason — As Y requires one electron to complete its octet, so two atoms of Y will share one electron each in a covalent bond to form a molecule of Y.

(c) Y is bad conductor of electricity.
Reason — As Y is a non-metal, hence it is a bad conductor of electricity.

Question 8(i)

Identify the anion present in each of the following compounds.

(a) Compound Z which on reacting with dilute sulphuric acid liberates a gas which has no effect on acidified potassium dichromate but turns lime water milky.

(b) The solution of compound L on reacting with freshly prepared ferrous sulphate solution followed by addition of few drops of concentrated sulphuric acid to the reactants along the sides of a test tube forms a brown ring at the junction of the two liquids.

Answer

(a) CO₃^2- (Carbonate)

(b) NO₃^- (Nitrate)

Question 8(ii)

(a) Neeraj observed that the stain of curry on a white shirt becomes reddish brown when baking soda is scrubbed on it, but it turns yellow again when the shirt is washed with plenty of water. What might be the reason for his observation?

(b) Write the equation for the preparation of ethanoic acid from ethanol.

Answer

(a) The curry stain is yellow due to presence of turmeric in it. Turmeric is a natural indicator and is sensitive to changes in pH value. Baking soda is a basic substance hence when it is scrubbed on the curry stain, the turmeric changes to reddish brown colour. On washing, the water rinsed away the baking soda as well as the top layer of turmeric that changed colour. So the stain turned yellow again.

(b) Ethanoic acid from ethanol

$\underset{ \text{ ethanol[ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanal [acetaldehyde] }}{\text{CH}_3\text{CHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{ \text{ethanoic acid[acetic acid]} }{\text{CH}_3\text{COOH}}$

Question 8(iii)

(a) State whether the following statements are True or False.

1. Electrovalent compounds have low melting point.

2. Carbon tetrachloride will conduct electricity only in aqueous solution state.

(b) Give reason - Hydrogen chloride can be termed as a polar covalent compound.

Answer

(a)

1. False
   Reason — Electrovalent compounds have a high melting point and boiling point because there exists a strong force of attraction between the oppositely charged ions, so a large amount of energy is required to break the strong bonding force between ions.

2. False
   Reason — Carbon tetrachloride (CCl₄) is a liquid that does not conduct electricity because it is a non-polar covalent compound. In the case of CCl₄, carbon atom shares electrons with four chlorine atoms. The electrons are shared equally between the atoms, and the molecule has no permanent dipole moment, meaning there is no separation of charge. Therefore, there are no ions present in the compound, and no free electrons to carry an electrical current.

(b) Chlorine exhibits a higher electronegativity than hydrogen, causing it to attract the shared pair of electrons towards itself in the bond. As a result, chlorine develops a slight negative charge and hydrogen develops a slight positive charge. Hence, the bond formed between hydrogen and chlorine is termed a polar covalent bond, and the compound is classified as a polar covalent compound.

Question 8(iv)

Choose the correct word which refers to the process of electrolysis from A to C to match the description 1 to 3.

A : Oxidation
B : Cathode
C : An electrolyte

(1) Can conduct electricity in aqueous or in molten state ...............

(2) Loss of electron takes place at anode is called ...............

(3) A reducing electrode is ...............

Answer

(1) C : An electrolyte

(2) A : Oxidation

(3) B : Cathode