Solved Sample Paper 1

Section A

Question 1(i)

Which of the given options correctly represents the parent acid and base of potassium nitrate?

1. W
2. X
3. Y
4. Z

Answer

Y

Reason — Potassium hydroxide (a base) reacts with nitric acid (an acid) to produce potassium nitrate (salt) and water.

HNO₃ + KOH ⟶ H₂O + KNO₃

Question 1(ii)

The bond between carbon and hydrogen in a molecule of methane is

1. single covalent bond
2. double covalent bond
3. triple covalent bond
4. ionic bond

Answer

single covalent bond

Reason — In a molecule of methane, one carbon atom forms four covalent bonds with four hydrogen atoms by sharing a pair of electrons between itself and each hydrogen (H) atom.

Question 1(iii)

During the Ostwald's process, the gaseous reactants used are

1. nitrogen and oxygen
2. oxygen and carbon dioxide
3. chlorine and nitrogen
4. ammonia and oxygen

Answer

ammonia and oxygen

Reason —

$4\text{NH}_3 + 5\text{O}_2 \xrightarrow[700-800 \degree\text{C}]{\text{Pt}} 4\text{NO} + 6\text{H}_2\text{O} + 21.5 \text{K cals}$

Question 1(iv)

If the molecular weight of molecule increases then the melting point of alkenes.

1. Increases
2. Decreases
3. Constant
4. Does not depend on molecular weight

Answer

increases

Reason — Melting point, boiling point, density etc. of the successive members of the homologous series increase with increase in molecular mass.

Question 1(v)

Identify the correct setup in the following experiment

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

Answer

B

Reason — On heating sodium hydrogen carbonate, carbon dioxide gas is evolved which turns lime water milky.

Question 1(vi)

IUPAC name of formic acid.

1. Ethanoic acid
2. Propanoic acid
3. Butanoic acid
4. Methanoic acid

Answer

Methanoic acid

Reason — The IUPAC name of formic acid [HCOOH] is methanoic acid.

Question 1(vii)

Carbon to carbon double bond is found in

1. 2-butylene
2. acetaldehyde
3. acetic acid
4. ethyl alcohol

Answer

2-butylene

Reason — Carbon to carbon double bond is found in 2-butylene.

Question 1(viii)

The base that neutralizes the acidity in stomach and acts as an antacid

1. Ammonium hydroxide
2. Aluminium hydroxide
3. Magnesium hydroxide
4. Calcium oxide

Answer

Magnesium hydroxide

Reason — Magnesium hydroxide also known as milk of magnesia is a common component of antacids.

Question 1(ix)

Reaction of zinc metal with sodium hydroxide will lead to the formation of

1. sodium zincate
2. sodium chloride
3. zinc hydroxide
4. zinc aluminate

Answer

sodium zincate

Reason — Zn + 2NaOH ⟶ H₂ + Na₂ZnO₂ [sodium zincate]

Question 1(x)

The 'n' of CH₃ is 3. Then, the molecular formula is

1. C₃H₆
2. C₃H₉
3. CH
4. CH₉

Answer

C₃H₉

Reason — As, molecular formula = n x empirical formula

Hence, molecular formula = 3 x CH₃ = C₃H₉

Therefore, the molecular formula of the compound is C₃H₉

Question 1(xi)

During the electrolysis of aqueous copper sulphate using copper electrodes, copper ions are generated at the anode that go into the copper sulphate solution used as electrolyte.

Which of the following is correct regarding the mass of anode

P. Mass of anode remains same
Q. Mass of anode gradually decreases
R. Mass of anode gradually increases

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

Answer

Only Q

Reason — SO₄^2- and OH^1- ions migrate to the anode but neither are discharged since the copper anode loses electrons more easily than SO₄^2- and OH^1-. Hence, copper anode shows a loss in mass.

Question 1(xii)

The element which will have highest ionization potential is ...............

1. calcium
2. fluorine
3. helium
4. neon

Answer

Helium

Reason — Helium has highest ionization potential because ionization potential increases from left to right across a period and decreases down a group.

Question 1(xiii)

During electrolytic reduction of molten alumina, aluminium metal is obtained at

1. carbon cathode
2. carbon anode
3. aluminium anode
4. aluminium cathode

Answer

carbon cathode

Reason — At cathode :

2Al³⁺ + 6e^- ⟶ 2Al

At anode : 3O^2- - 6e^- ⟶ 3[O] ⟶ 3O₂

Al³⁺ are discharged in preference to Na¹⁺ and Ca²⁺ ions due to it's lower position in the electrochemical series.

Question 1(xiv)

When fused lead bromide is electrolysed we observe

1. silver fumes at cathode
2. silver fumes at anode
3. reddish brown fumes formed at anode
4. reddish brown fumes formed at cathode

Answer

reddish brown fumes formed at anode

Reason — Reddish brown fumes of bromine evolve at the anode and silvery gray metal lead is formed on the cathode.

Question 1(xv)

The atomic masses of nitrogen (N), oxygen (O) and neon (Ne) are approximately 14, 16 and 20.18 respectively.

Which of the following statements regarding the number of atoms in 14 g of nitrogen, 16 g of oxygen and 20 g of neon is correct?

P. 14 g of nitrogen contains double number of atoms as 20 g of neon.

Q. 16 g of oxygen contains two times the number of atoms as 14 g of nitrogen.

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

Answer

Neither P nor Q

Reason — According to Avogadro's number (N_A) = 6.022 x 10²³ atoms are present in one mole of element.

In case of P,

Number of atoms in 14 g of N

= $\dfrac{\text{Given mass}}{\text{Atomic mass}}$ x N_A

= $\dfrac{14}{14}$ X 6.022 x 10²³

= 6.022 x 10²³

Number of atoms in 20 g of Ne

= $\dfrac{\text{Given mass}}{\text{Atomic mass}}$ x N_A

= $\dfrac{20}{20.18}$ X 6.022 x 10²³

= 0.99 x 6.022 x 10²³

= 5.96 x 10²³ atoms

As number of atoms in 14 g of nitrogen is almost equal to 20 g of Neon. Hence, statement P is incorrect.

In case of statement Q,

Number of atoms in 16 g of oxygen

= $\dfrac{\text{Given mass}}{\text{Atomic mass mass}}$ X N_A

= $\dfrac{16}{16}$ X 6.022 x 10²³

= 6.022 x 10²³

As number of atoms in 16 g of oxygen is equal to 14 g of nitrogen. Hence, statement Q is also incorrect.

Question 2(i)

The diagram shows an experimental set up for the laboratory preparation of a gas known as marsh gas. It is also present in the air exhaled by animals whose food contain cellulose. Study the diagram and answer the following.

(a) Name the gas collected in the jar.

(b) Write a balanced chemical equation for the above preparation. How is the gas being collected?

(c) Name the type of reaction taking place in this. Why this particular reaction is taking place in this?

Answer

(a) Methane [CH₄]

(b)

$\underset{\text{sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{methane}}{\text{CH}_4} + \text{Na}_2\text{CO}_3$

The gas is collected by downward displacement of water.

(c) Decarboxylation reaction takes place. It happens due to elimination of a molecule of CO₂ from a carboxylic acid. In this reaction, CO₂ is removed as a carbonate.

Question 2(ii)

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

(a) On moving down the group electron affinity ............... (increases/decreases).

(b) The functional group present in acetic acid is ............... (-COOH/-OH/-CHO)

(c) ............... (Concentrated sulphuric acid/Dilute sulphuric acid) is a weak acid and a good electrolyte.

(d) Compounds which contains one —COOH group are known as ............... (monocarboxylic acid/dicarboxylic acid).

(e) Quicklime is not used to dry HCl gas because CaO is ............... (alkaline/acidic) in nature.

Answer

(a) On moving down the group electron affinity decreases.

(b) The functional group present in acetic acid is —COOH.

(c) Dilute sulphuric acid is a weak acid and a good electrolyte.

(d) Compounds which contains one —COOH group are known as monocarboxylic acid.

(e) Quicklime is not used to dry HCl gas because CaO is alkaline in nature.

Question 2(iii)

Match the following Column I with Column II

Answer

Question 2(iv)

Identify the following

(a) The reaction by which salt and water is formed.

(b) The metal which is kept in kerosene oil due to its high reactivity.

(c) A base which is soluble in water.

(d) A gas is evolved when liquor ammonia is exposed to air.

(e) A colourless gas which becomes reddish brown when it comes in contact with atmosphere.

Answer

(a) Neutralization reaction

(b) Sodium (Na)

(c) Alkali

(d) Ammonia

(e) Nitric oxide

Question 2(v)

(a) Draw the structural formula for the following.

(1) But-1-ene

(2) Butanoic acid

(3) Propanol

(b) Name the following organic compounds in IUPAC system

Answer

(a) Structural formulae are shown below:

(1) But-1-ene

(2) Butanoic acid

(3) Propanol

(b) IUPAC names of the organic compounds are:

(1) Methanoic acid

(2) 3-methyl-hexane

Section B

Question 3(i)

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

Sodium ethanoate reacts with compound Q to give a strong base Na₂CO₃ and CH₄.

Answer

The compound Q is sodalime [NaOH]

$\underset{\text{sodium ethanoate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{methane}}{\text{CH}_4} + \text{Na}_2\text{CO}_3$

Question 3(ii)

Name the gas evolved in each of the following cases.

(a) Reaction of sodium with conc. HCl

(b) Reaction of sodium thiosulphate with HCl.

Answer

(a) Hydrogen gas

(b) Sulphur dioxide gas

Question 3(iii)

Write the balanced chemical equation for the following.

(a) Lead nitrate is treated with hydrochloric acid.

(b) Zinc oxide is treated with potassium hydroxide.

(c) Silver nitrate is treated with sodium cyanide.

Answer

(a) Pb(NO₃)₂ + 2HCl ⟶ PbCl₂ ↓ + 2HNO₃

(b) ZnO + 2KOH ⟶ K₂ZnO₂ + H₂O

(c) AgNO₃ + NaCN ⟶ AgCN ↓ + NaNO₃

Question 3(iv)

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

(1) According to Mendeleev, periodic properties of elements are periodic functions of their atomic number.

(2) Non-metals form oxides that are basic in nature.

(b) Write the chemical reaction of Ammonium hydroxide with soluble salt of lead (Pb²⁺ ion).

Answer

(a) (1) False
Corrected Statement — According to Mendeleev, periodic properties of elements are periodic functions of their atomic weight.

(a) (2) False.
Corrected Statement — Metals form oxide that are basic in nature.

(b) Pb(NO₃)₂ + 2NH₄OH ⟶ Pb(OH)₂ ↓ + 2NH₄NO₃

Question 4(i)

Define:

(a) Covalent bond

(b) Co-ordinate bond

Answer

(a) Covalent bond — The chemical bond that is formed between two combining atoms by mutual sharing of one or more pair of electrons is called a covalent bond. Depending on the number of electron pairs shared : bond is single [-], double [=], or triple [≡] covalent.

(b) Co-ordinate bond — The bond formed between two atoms by sharing a pair of electrons, provided entirely by one of the combining atoms but shared by both is called a coordinate bond.

Question 4(ii)

Solve

A compound has the following percentage composition by mass, carbon 14.4%. hydrogen 1.2% and chlorine 84.5%. Determine the empirical formula of this compound. (H=1, C=12 and Cl=35.5)

Answer

Simplest ratio of whole numbers = C : H : Cl = 1 : 1 : 2

Hence, empirical formula is CHCl₂

Question 4(iii)

State the conditions required for the following reactions

(a) Conversion of potassium nitrate to potassium bisulphate.

(b) Conversion of nitrogen and hydrogen to ammonia.

(c) Conversion of ammonia to nitric oxide.

Answer

(a) Conditions required for the conversion of potassium nitrate to potassium bisulphate are:

1. Temperature of the reaction should not exceed 200°C.
2. All glass apparatus should be used.
3. Reaction:
   KNO₃ + H₂SO₄ $\xrightarrow{\lt 200 \degree\text{C}}$ KHSO₄ + HNO₃

(b) Conditions required for the conversion of nitrogen and hydrogen to ammonia are:

1. Temperature should be between 450-500°C.
2. Pressure should be above 200 atm.
3. Catalyst used is finely divided iron.
4. Promoter used is traces of molybdenum or Al₂O₃.
5. Reaction:
   N₂ + 3H₂ $\xrightleftharpoons[450-500\text{°C},\text { above }200 \text{ atm}]{\text{Fe and Mo}}$ 2NH₃ + Δ

(c) Conditions required for the conversion of ammonia to nitric oxide are:

1. Temperature should be around 800°C.
2. Catalyst used is Platinum.
3. Reaction:
   4NH₃ + 5O₂ $\xrightarrow[800 \degree \text{C}]{\text{Pt}.}$ 4NO↑ + 6H₂O + Δ
   2NO + O₂ ⟶ 2NO₂ (brown gas)

Question 4(iv)

Choose the role played by alloys given as A, B, C with 1 to 3.

A. Solder

B. Duralumin

C. Stainless steel

1. It is stronger than aluminium, has light weight and is used in making aircraft frames.

2. It is lustrous, hard, corrosion resistant and used in surgical instruments.

3. It lowers the melting point of the alloy and is used for soldering purpose.

Answer

1. Duralumin
2. Stainless steel
3. Solder

Question 5(i)

Identify the catalyst used and the compound formed from the following observation.

(a) A catalyst used in the manufacture of nitric acid by Ostwald's process.

(b) A compound formed when both sulphur trioxide and sulphuric acid reacts.

Answer

(a) Platinum gauze

(b) Oleum or pyrosulphuric acid (H₂S₂O₇)

Question 5(ii)

Write the products and balance the equation.

(a) NH₄OH + HCl ⟶

(b) ZnS + HCl ⟶

Answer

(a) The products formed are Ammonium chloride and Water.
NH₄OH + HCl ⟶ NH₄Cl + H₂O

(b) The products formed are Zinc chloride and Hydrogen gas.
ZnS + 2HCl ⟶ ZnCl₂ + H₂S ↑

Question 5(iii)

Arrange the following as per the instructions given in the brackets.

(a) Al, Cl, Na, Si, Mg (increasing order of non-metallic character).

(b) C, F, Li, O, Be (decreasing order of metallic character)

(c) Mg, Al, Na, Si (increasing order of atomic size).

Answer

(a) Na < Mg < Al < Si < Cl

(b) Li > Be > C > O > F

(c) Si < Al < Mg < Na

Question 5(iv)

X [Oxygen, Sulphur, Selenium] and Y [Neon, Argon, Xenon] are two sets of elements. Using these elements complete the following.

(a) Set ............... is known as noble gases.

(b) In set X ............... has the highest electronegativity.

(c) The ............... set contains the non-metals.

Answer

(a) Set Y is known as noble gases.

(b) In set X oxygen has the highest electronegativity.

(c) The X set contains the non-metals.

Question 6(i)

(a) For each of the substances given below, what is the role played in the preparation of NH₃ (ammonia)

(a) CaO

(b) Mo

Answer

(a) CaO is used as a drying agent. In order to get dry ammonia, the gas is passed through a drying tower containing lumps of quicklime [CaO].

(b) Mo acts as a promoter i.e., it increases the efficiency of the catalyst.

Question 6(ii)

Calculate:

(a) The mass of 12.044 x 10²³ oxygen atoms.

(b) What is the vapour density of ethylene?

Answer

(a) No. of moles of oxygen atoms = $\dfrac{12.044 \times 10^{23}}{6.022 \times 10^{23}}$ = 2 moles

Mass of oxygen atoms = no. of moles x atomic mass

= 2 x 16 = 32 g.

∴ The mass of 12.044 x 10²³ oxygen atoms is 32 grams.

(b) Gram molecular mass of ethylene (C₂H₄) = 2(12) + 4(1) = 24 + 4 = 28 g

Vapour density = $\dfrac{\text{Molecular weight}}{2}$ = $\dfrac{28}{2}$ = 14

Hence, vapour density is 14

Question 6(iii)

The following questions are asked with respect to the electrolytic process in the extraction of aluminium.

(a) Identify the components of the electrolyte other than pure alumina.

(b) Give the role played by these components.

Answer

(a) Cryolite and fluorspar are components of the electrolyte.

(b) Addition of cryolite lowers the fusion temperature from 2050°C to 950°C and enhances conductivity. Both cryolite & fluorspar act as a solvent for the electrolytic mixture and increase its conductivity since pure alumina is almost a non-conductor of electricity.

Question 6(iv)

Rajat mixed a white coloured compound A with water. The compound A reacted vigorously with water to produce a compound B and large amount of heat. He used the compound B to white wash the walls.

After 3 days of whitewash, the walls became shiny

(a) Name the compound A

(b) Why the walls appear shiny ? Write the reactions involved.

(c) State the type of reaction occurred here.

Answer

(a) Calcium oxide [CaO]

(b) The walls appeared shiny on the 3rd day due to the reaction of calcium hydroxide with carbon dioxide present in the air to produce white-colored calcium carbonate.

CaO + H₂O ⟶ Ca(OH)₂ + heat
Ca(OH)₂ (aq) + CO₂ (g) ⟶ CaCO₃ (s) + H₂O (l)

(c) Precipitation reaction

Question 7(i)

(a) Name the particles present in

1. Lead chloride
2. Potassium nitrate

(b) Explain why powdered coke is sprinkled over the electrolytic mixture ?

Answer

(a) The following particles are present in:

1. Lead chloride — Pb²⁺ and Cl^1-
2. Potassium nitrate — K¹⁺ and NO₃^1-

(b) The layer of powdered coke is sprinkled over the electrolytic mixture as:

1. It prevents burning of carbon electrodes in air at the emergence point from the bath.
2. It minimizes or prevents heat loss by radiation.

Question 7(ii)

Consider the elements ₈B, ₂₀A. What type of bond will be formed when element B and A react with each other. Also find out in which group, A and B elements are present in the periodic table.

Answer

Electronic configuration of ₈B is [2, 6]. It needs two electrons to complete its octet.

Electronic configuration of ₂₀A is [2, 8, 8, 2]. It wants to donate two electrons in order to obtain a stable octet configuration.

Hence, ionic bond is formed as ₂₀A loses two electrons and ₈B gains two electrons and both attain a stable octet.

₈B [2, 6] is present in group VIA and ₂₀A [2, 8, 8, 2] is present in group in IIA as the group of an elements is predicted from the number of electrons in the valence shell.

Question 7(iii)

(a) List any two uses of ammonia.

(b) Give the balanced equations for the following conversions

1. Ammonia solution to an amphoteric hydroxide
2. Ammonia to brown gas

Answer

(a) Two uses of ammonia are:

1. Liquid ammonia is used as a refrigerant in ice plants.
2. Ammonia is used in the manufacture of nitrogenous fertilisers like ammonium sulphate, ammonium nitrate, urea, etc.

(b) Balanced equations for the conversions are given below:

1. AlCl₃ (aq) + 3NH₄OH (aq) ⟶ Al(OH)₃ ↓ + 3NH₄Cl (aq)

2. 4NH₃ + 5O₂ $\xrightarrow[800 \degree \text{C}]{\text{Pt}.}$ 4NO↑ + 6H₂O + Δ
   2NO + O₂ ⟶ 2NO₂ (brown gas)

Question 8(i)

Identify the functional group in the following organic compounds.

Answer

(a) The functional group present is -COOH (carboxylic acid).

(b) The functional group present is -OH (alcohol).

Question 8(ii)

The empirical formula and molecular mass of a compound are CH₂O and 180 g respectively. What will be the molecular formula of the compound?

Answer

Given,

empirical formula = CH₂O

Hence, empirical formula mass = 12 + 2(1) + 16 = 12 + 2 + 16 = 30 g

molecular formula = n x empirical formula

where,

n = $\dfrac{\text{molecular mass}}{\text{empirical formula mass}}$

∴ n = $\dfrac{180}{30}$ = 6

Hence, molecular formula = 6 x CH₂O = C₆H₁₂O₆

Therefore, the molecular formula of the compound is C₆H₁₂O₆

Question 8(iii)

Choose the most appropriate option from the following list of elements which fit in the description. Each option may be used only once.

[Aluminium, helium, carbon, phosphorous, sodium, potassium, argon, hydrogen]

(a) An element with variable (more than one) valency and stored in water.

(b) An element present in period 3 and group I of the periodic table.

(c) An element which is an inert gas with atomic number 2.

Answer

(a) Phosphorous [P]

(b) Sodium [Na]

(c) Helium [He]

Question 8(iv)

Give balanced equations for the following:

(a) Preparation of ethane from iodomethane.

(b) Preparation of ethyne from calcium carbide.

(c) Preparation of ethene from ethanol.

Answer

(a) 2CH₃I + 2Na $\xrightarrow[\text{ether}]{\text{dry}}$ C₂H₆ ↑ + 2NaI

(b) CaC₂ + 2H₂O ⟶ C₂H₂ ↑ + Ca(OH)₂

(c) C₂H₅OH $\xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4}$ C₂H₄ ↑ + H₂O