Q: Question 2(iv)Complete the following by choosing the correct answers from the bracket.(a) The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called ............... (electronegativity / electron affinity).(b) Electrolysis of aqueous copper sulphate will form ............... (copper metal / copper (II) ions) at cathode.(c) Quick lime is not used to dry HCl gas because it is ............... (alkaline/acidic) in nature.(d) The fusible compound formed by the combination of flux and gangue is called ................(mineral/slag).(e) ............... (Hydrochloric acid/Acetic acid) is used in the digestion of proteins.

(a) The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called electronegativity(b) Electrolysis of aqueous copper sulphate will form copper metal at cathode.(c) Quick lime is not used to dry HCl gas because it is alkaline in nature.(d) The fusible compound formed by the combination of flux and gangue is called slag .(e) Hydrochloric acid is used in the digestion of proteins.

Q: Question 2(v)(a) Draw the structural formula for the following.(1) 1,1-dichloroethane(2) Butyne(3) Ethan-1-al(b) Name the following organic compounds in IUPAC system.

(a) Structural formulae are shown below:(1) 1,1-dichloroethane(2) Butyne(3) Ethan-1-al(b) IUPAC names of the organic compounds are:(1) 2-propanone(2) 2,3-dimethyl butane

Q: Question 3(ii)Distinguish between the following as directed.(a) Calcium nitrate and lead nitrate using NaOH.(b) Ferrous chloride and ferric chloride using NH4OH.

(a) When sodium hydroxide (NaOH) solution is added to each of the compounds, lead nitrate forms a chalky white precipitate of lead hydroxide [Pb(OH)2] which is soluble in excess of sodium hydroxide and readily soluble in acetic acid.Pb(NO3)2 + 2NaOH ⟶ Pb(OH)2 ↓ + 2NaNO3Pb(OH)2 + 2NaOH (excess) ⟶ Na2PbO2 + 2H2OWhereas a milky white precipitate is formed in case of calcium nitrate which is sparingly soluble in excess of NaOH.Ca(NO3)2 + 2NaOH ⟶ Ca(OH)2 ↓ + 2NaNO3(b) On reaction with ammonium hydroxide (NH4OH), ferrous chloride forms a dirty green ppt whereas ferric chloride forms a reddish brown ppt. Hence, the two can be distinguished easily.FeCl2 + 2NH4OH ⟶ Fe(OH)2 ↓ + 2NH4ClFeCl3 + 3NH4OH ⟶ Fe(OH)3 ↓ + 3NH4Cl

Q: Question 3(iii)Name the ions present in(a) hydrogen chloride(b) lead sulphate(c) ammonium hydroxide

The ions are present are:(a) hydrogen chloride — H+ and Cl-(b) lead sulphate — Pb2+ and SO42-(c) ammonium hydroxide — NH4+ and OH-

Question 1

Question 1(iv)Which of the following electrolyte is used in the process of nickle plating?Silver nitratePotassium argentocyanideNickle ammonium sulphateCarbon rods

Accepted Answer

Nickle ammonium sulphateReason — In electroplating, the electrolyte must be a suitable salt of the plating metal. Hence, in nickle plating, nickle ammonium sulphate will be the electrolyte.

Question 2

Question 1(v)The empirical formula of hexane isC3H7C6H14C3H8C4H12

Accepted Answer

C3H7Reason — Molecular formula of hexane is C6H14∴ Ratio of C and H is 6 : 14Simple ratio is 3 : 7Hence, empirical formula = C3H7

Question 3

Question 1(x)The table shown below gives information about four substances A, B, C and DSubstancepH ValueA8.7B5.5C1.7D12.3Identify the basic compounds from the above given substances.A and BB and CA and DC and D

Accepted Answer

A and DReason — Substances having pH value greater than 7 are considered as basic substances. Hence, A and D in the given table are basic.

Question 4

Question 1(xii)A compound which liberates reddish brown gas around the anode during electrolysis in its molten state islead (II) nitratelead (II) sulphatelead (II) oxalatelead (II) bromide

Accepted Answer

lead (II) bromideReason — During electrolysis of Lead [II] bromide, Br-1 ions are discharged at the anode. Reddish brown fumes are due to bromine vapours.Reaction at anode:Br- - e- ⟶ BrBr + Br ⟶ Br2

Question 5

Question 2(i)Identify the following.(a)	Anode used in the electro refining of copper.(b)	A strong but non-volatile mineral acid.(c)	Name the process by which bauxite ore is purified.(d)	Name the process by which purified bauxite undergoes electrolytic reduction.(e)	The process of formation of positive and negative charge ions from molecules which are not initially in the ionic state.

Accepted Answer

(a) Impure copper(b) Sulphuric acid [H2SO4](c) Baeyer's process(d) Hall-Heroult's process(e) Ionisation

Question 6

Question 2(iii)The following diagram shows an experimental set up for the laboratory preparation of pungent choking gas. The gas is acidic in nature.(a) Name the gas collected in the jar and write the balanced chemical equation for the above preparation.(b)	How is the gas purified?(c)	Write the reaction of the gas produced with magnesium and ammonia.

Accepted Answer

(a) Hydrogen Chloride (HCl) gas.NaCl+H2SO4→<200°CNaHSO4+HCl [g]	ext{NaCl} + 	ext{H}_2	ext{SO}_4 \xrightarrow{\lt 200 \degree	ext{C}} 	ext{NaHSO}_4 + 	ext{HCl [g]}NaCl+H2​SO4​<200°C​NaHSO4​+HCl [g](b) By passing through conc. H2SO4.(c) Mg + 2HCl ⟶ MgCl2 + H2     NH3 ↑ + HCl ↑ ⟶ NH4Cl (s)

Question 7

Question 2(iv)Complete the following by choosing the correct answers from the bracket.(a)	The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called ............... (electronegativity / electron affinity).(b) Electrolysis of aqueous copper sulphate will form ............... (copper metal / copper (II) ions) at cathode.(c) Quick lime is not used to dry HCl gas because it is ...............	(alkaline/acidic) in nature.(d) The fusible compound formed by the combination of flux and gangue is called ................(mineral/slag).(e) ............... (Hydrochloric acid/Acetic acid) is used in the digestion of proteins.

Accepted Answer

(a)	The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called electronegativity(b) Electrolysis of aqueous copper sulphate will form copper metal at cathode.(c) Quick lime is not used to dry HCl gas because it is	alkaline in nature.(d) The fusible compound formed by the combination of flux and gangue is called slag .(e) Hydrochloric acid is used in the digestion of proteins.

Question 8

Question 2(v)(a) Draw the structural formula for the following.(1) 1,1-dichloroethane(2) Butyne(3) Ethan-1-al(b)	Name the following organic compounds in IUPAC system.

Accepted Answer

(a) Structural formulae are shown below:(1) 1,1-dichloroethane(2) Butyne(3) Ethan-1-al(b)	IUPAC names of the organic compounds are:(1) 2-propanone(2) 2,3-dimethyl butane

Question 9

Question 3(i)Draw the electron dot structure for the following.(a) H2SO4(b) CO2

Accepted Answer

(a) H2SO4(b) CO2

Question 10

Question 3(ii)Distinguish between	the following as directed.(a) Calcium nitrate and lead nitrate using NaOH.(b)	Ferrous chloride and ferric chloride using NH4OH.

Accepted Answer

(a) When sodium hydroxide (NaOH) solution is added to each of the compounds, lead nitrate forms a chalky white precipitate of lead hydroxide [Pb(OH)2] which is soluble in excess of sodium hydroxide and readily soluble in acetic acid.Pb(NO3)2 + 2NaOH ⟶ Pb(OH)2 ↓ + 2NaNO3Pb(OH)2 + 2NaOH (excess) ⟶ Na2PbO2 + 2H2OWhereas a milky white precipitate is formed in case of calcium nitrate which is sparingly soluble in excess of NaOH.Ca(NO3)2 + 2NaOH ⟶ Ca(OH)2 ↓ + 2NaNO3(b) On reaction with ammonium hydroxide (NH4OH), ferrous chloride forms a dirty green ppt whereas ferric chloride forms a reddish brown ppt. Hence, the two can be distinguished easily.FeCl2 + 2NH4OH ⟶ Fe(OH)2 ↓ + 2NH4ClFeCl3 + 3NH4OH ⟶ Fe(OH)3 ↓ + 3NH4Cl

Question 11

Question 3(iii)Name the ions present in(a)	hydrogen chloride(b)	lead sulphate(c)	ammonium hydroxide

Accepted Answer

The ions are present are:(a) hydrogen chloride — H+ and Cl-(b) lead sulphate — Pb2+ and SO42-(c) ammonium hydroxide — NH4+ and OH-

Question 12

Question 4(ii)Write the products and balance the equation.(a)	Na2CO3 + H2SO4 ⟶(b) Fe + H2SO4 ⟶

Accepted Answer

(a)	Na2CO3 + H2SO4 ⟶ Na2SO4 + H2O + CO2 ↑The products formed are sodium sulphate, water and carbon dioxide gas.(b) Fe + H2SO4 ⟶ FeSO4 + H2 ↑The products formed are ferrous sulphate and hydrogen gas.

Question 13

Question 4(iii)Calcium, cobalt, nitrogen, magnesium, and silicon are some elements. Using this information complete the following.(a)	............... is the most reactive metal.(b)	............... is a metalloid.(c) ...............	is a non-metal.

Accepted Answer

(a)	Calcium is the most reactive metal.(b)	Silicon is a metalloid.(c) Nitrogen is a non-metal.

Question 14

Question 4(iv)Give reasons:(a)	Covalent compounds have low melting point.(b) For covalent bond formation both atoms should have high ionisation.(c)	Covalent bond formation takes place when both atoms should have four or more electron in outermost shell.

Accepted Answer

(a) Covalent compounds have low melting and boiling points because they have weak forces of attraction between the binding molecules, thus less energy is required to break the force of bonding.(b) When both atoms have high ionisation, the energy required to remove electrons from them is very large. Thus, transfer of electrons is not possible. The atoms share electrons to complete their octet. Hence they form covalent bonds.(c) The atoms that have four or more electrons in outermost shell do not favour the loss of their electrons due to energy considerations and thus transfer of electrons is not possible. So, they form covalent bonds to achieve stable electronic configuration.

Question 15

Question 5(i)Glucose or blood sugar has the molecular formula C6H12O6. Determine % of each element.

Accepted Answer

Percentage of particular element = MassTotal mass\dfrac{	ext{Mass}}{	ext{Total mass}}Total massMass​ x 100C6H12O6 = 6(12) + 12(1) + 6(16) = 72 + 12 + 96 = 180 g per molePercentage of C = 72180\dfrac{72}{180}18072​ x 100 = 40%Percentage of H = 12180\dfrac{12}{180}18012​ x 100 = 6.67%Percentage of O = 96180\dfrac{96}{180}18096​ x 100 = 53.33%Hence, Percentage of C = 40%, H = 6.67% and O = 53.33%

Question 16

Question 5(iii)(a) State whether the following statements are true or false. Justify your answer.(1)	Electrolysis of molten lead bromide is considered to be a redox reaction.(2)	Copper is a good conductor of electricity but it is a non-electrolyte.(b)	State the reaction occurring at the anode during electrolysis of copper sulphate solution using a copper anode and platinum anode respectively.

Accepted Answer

(a) (i) TrueElectrolysis of molten lead bromide involves oxidation and reduction reactions and hence is a redox reaction.Dissociation of lead bromidePbBr2 ⇌ Pb2+ + 2Br1-Reduction reaction at cathode:Pb2+ + 2e- ⟶ PbOxidation reaction at the anode:Br1- - 1e- ⟶ BrBr + Br ⟶ Br2(a) (ii) TrueCopper does not undergo chemical decomposition due to flow of electric current through it. Hence, copper is a good conductor of electricity but it is a non-electrolyte.(b) Reaction at anode [active copper] : Cu - 2e- ⟶ Cu2+Reaction at anode [inert platinum] : OH1- - 1e- ⟶ OH x 44OH ⟶ 2H2O + O2

Question 17

Question 6(i)For each of the substance given below, write the constituents and one use of the following alloys.(a)	Duralumin(b)	Solder

Accepted Answer

(a)	Duralumin — Al [95%], Mg [0.5%], Mn [0.5%], Cu [4%]It is used for making bodies of aircraft.(b)	Solder — Pb [50%], Sn [50%]It is used for soldering purposes.

Question 18

Question 6(ii)Calculate:(a)	A compound contains 69.5% oxygen, 30.5% nitrogen and its molecular weight is 92. Then what will be the molecular formula of the compound?(b) If the empirical formula of a compound is CHO and its vapour density is 29, find the molecular formula of the compound.

Accepted Answer

Element% compositionAt. wt.Relative no. of atomsSimplest ratioO69.51669.516\dfrac{69.5}{16}1669.5​ = 4.344.342.17\dfrac{4.34}{2.17}2.174.34​ = 2N30.51430.514\dfrac{30.5}{14}1430.5​ = 2.172.172.17\dfrac{2.17}{2.17}2.172.17​ = 1Simplest ratio of whole numbers = O : N = 2 : 1Hence, empirical formula is NO2Molecular weight = 92Empirical formula weight = 14 + 2(16) = 14 + 32 = 46n=Molecular weightEmpirical formula weight=9246=2\text{n} = \dfrac{\text{Molecular weight}}{\text{Empirical formula weight}} \[0.5em] = \dfrac{92}{46} = 2n=Empirical formula weightMolecular weight​=4692​=2Molecular formula = n[E.F.] = 2[NO2] = N2O4Hence, molecular formula is N2O4.(b) Empirical formula of the compound = CHOEmpirical formula mass = 12 + 1 + 16 = 29Molecular formula mass = 2 x vapour density= 2 x 29 = 58 gMolecular formula = (Empirical formula)n∴ Molecular formula = (CHO)2 = C2H2O2

Question 19

Question 6(iii)Rahul performed an experiment for the preparation of sulphuric acid. Answer the following questions pertaining to it.(a) Name the process which is involved in this experiment used for the large scale manufacturing of sulphuric acid.(b) Which property of sulphuric acid accounts for its use as a dehydrating agent?(c) Concentrated sulphuric acid acts as both an oxidising agent and a non-volatile acid. Write one equation each to illustrate the above mentioned properties of sulphuric acid.

Accepted Answer

(a) Contact process(b) Sulphuric acid has a great affinity for water. It readily removes elements of water from other compounds. Hence, it is used as a dehydrating agent.(c) Concentrated sulphuric acid as an Oxidising agent:Cu + 2H2SO4 [conc.] ⟶ CuSO4 + 2H2O + 2SO2 ↑Concentrated sulphuric acid as a non-volatile acid:NaNO3 + H2SO4 [conc.] →<200°C\xrightarrow{\lt 200 \degree	ext{C}}<200°C​ NaHSO4 + HNO3

Question 20

Question 7(i)(a) State why ethyne burns in oxygen with a sooty flame?(b) Write the balanced chemical equation when water is added to calcium carbide.

Accepted Answer

(a) Ethyne being a hydrocarbon contains carbon hence, all the carbon particles do not oxidise completely. Thus, it burns with sooty flame.(b) CaC2calcium carbide+2H2Owater⟶C2H2ethyne [acetylene]+Ca(OH)2\underset{	ext{calcium carbide}}{	ext{CaC}_2} + \underset{	ext{water}}{2	ext{H}_2	ext{O}} \longrightarrow \underset{	ext{ethyne [acetylene]}}{	ext{C}_2	ext{H}_2} + 	ext{Ca(OH)}_2calcium carbideCaC2​​+water2H2​O​⟶ethyne [acetylene]C2​H2​​+Ca(OH)2​

Solved Sample Paper 2

Section A

Section B