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Chemistry

Mole Concept

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10 molal solution is prepared by dissolving x g of urea (Molar mass = 60 g mol–1 ) in 100 g of water. The value of x is:

60 g

30 g

120 g

180 g

6.022 × 10²¹ molecules of glucose are present in 100 mL of solution. The concentration of solution is:

0.1 M

0.01 M

1 M

10 M

One mole of which species has maximum number of electrons?

N₃⁻

N³⁻

O₂⁺

O₂⁻

The moles of O₂ required for reacting with 6.8 g of ammonia is:

4NH₃ + 5O₂ → 4NO +6H₂O

2.5

0.5

Match List-I with List-II A. 3 mole of Fe3S2 B. 1 mole of FeSO4 C. 2 mole of O3 D. 1.5 mole of K2CO3

A-I, B-II, C-III, D-IV

A-II, B-III, C-I, D-IV

A-III, B-IV, C-II, D-I

A-IV, B-II, C-III, D-I

Given below are two statements:

Assertion (A): The reactant which gets consumed first, limits the amount of product formed.

Reason (R): The reactant which decides the amount of product formed is called excess reagent.

In the light of the above statements, choose the correct answer from the options given below:

A is true but R is false.

A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Both A and R are true but R is NOT the correct explanation of A.

How many significant figures are in 0.0005?

What is the mass of oxygen required for the complete combustion of 2.8 kg of ethylene?

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

2.8 kg

6.4 kg

9.6 kg

6.9 kg

The number of molecules in 1 mL of CO₂ at STP is;

1.12 × 10²⁰

2.16 × 10²⁰

3.12 × 10²¹

2.69 × 10¹⁹

The number of atoms in 0.1 mole of a triatomic gas is;

6.026 × 10^22

1.807 × 10^23

3.600 × 10^23

1.800 × 10^22

Given below are two statements:

Statement-I: Vapour density of CH₄is half of O₂.

Statement-II: 1.6 g of CH₄ contains same number of electrons as 3.2 g of O₂.

In the light of the above statements, choose the most appropriate answer from the options given below:

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

Calculate the total number of moles in 5.6 L N₂.

0.5

0.75

0.25

0.05

Nitrogen and oxygen combines to form N₂O₅ and NO₂ containing 25.92% and 30.43% of Nitrogen respectively by mass, the data illustrates;

Law of conservation of mass.

Law of constant proportions.

Law of reciprocal proportions.

Law of multiple proportions.

Percentage of water in hydrated sodium carbonate (Na₂CO₃·10H₂O) is:

56%

76%

68%

63%

Which of the following is an example of a compound?

Sugar solution

Hydrogen

Ammonia

Sodium

112.0 mL of NO₂ at STP was liquefied, the density of the liquid being 1.15 g mL⁻¹. Calculate the number of molecules in the liquid NO₂ (At. wt. N = 14)

1.1 × 10²¹

3.1 × 10²¹

2.1 × 10¹⁵

4.1 × 10²¹

Which of the following phrases would be incorrect to use?

A mole of an element

A mole of a compound

An atom of an element

An atom of a compound

The mass of one ammonia (NH₃) molecule is:

17 g

17 N_A g

$\frac{17}{N _{A}}$ g

$\frac{N _{A}}{17}$ g

Equal masses of H₂, O₂ and CH₄ have been taken in a container of volume V at temperature 27°C in identical conditions. The ratio of the volumes of gases H₂ : O₂ : CH₄ would be;

8 : 16 : 1

16 : 8 : 1

16 : 1 : 2

8 : 1 : 2

An element Z contains two naturally occurring isotopes ₁₇Z³⁵ and ₁₇Z³⁷. If the average atomic mass is 35.5 u, then the percentage of two isotopes ₁₇Z³⁵ and ₁₇Z³⁷ repectively is:

75%, 25%

25%, 75%

85%, 15%

15%, 85%

A solution contains 4 mol of ethanol and 6 mol of water. The mole fraction of ethanol in the solution is;

0.6

0.2

0.8

0.4

Consider the following statements. A. 1 mole electrons are equal to 6.022 × 10^23 electrons. B. The mass of NA electrons is equal to 5.48 × 10^−7 kg C. Number of particle present in 1 mole of nitrogen atom are 6.023

Only A

Only C

Only B

A, B and C

The number of ions present in 2 L of a solution of 1.6 M Al₂(SO₄)₃ is:

4.8 × 10²²

4.8 × 10²³

9.6 × 10²⁴

9.6 × 10²²

Match List I with List II A.

List I	List II
A Vapour density	i 2N_A atoms
B 1 mole	ii 0.5 mole electrons
C 24 g carbon	iii Collection of N_Aparticles
D 3.01 × 10²³	iv Molecular Mass × $\frac{1}{2}$

A-IV, B-I, C-II, D-III

A-I, B-IV, C-III, D-II

A-III, B-I, C-II, D-IV

A-IV, B-III, C-I, D-II

Match List I with List II

Screenshot 2026-03-18 at 11.52.54 PM.png

Choose the correct answer from the options given below

A-II, B-I, C-IV, D-III

A-III, B-I, C-II, D-IV

A-I, B-II, C-IV, D-III

A-IV, B-II, C-III, D-I

The amount of H₂O formed by the reaction of 10 g of H₂with 64 g of O₂ is:

2 mol

2.5 mol

1.5 mol

4 mol

Formation of CO and CO2 illustrates the law of ;

Law of conservation of mass

Avogadro’s law

Law of Constant Proportion

Law of Multiple Proportion

Given below are two statements:

Statement I: The sum of mole fractions of all the components in a solution is always unity.

Statement II: One gram molecule of hydrogen contains N_A atoms of hydrogen.

In the light of the above statements, choose the most appropriate answer from the options given below:

Both correct

I correct II incorrect

I incorrect II correct

Both incorrect

The maximum amount of BaSO₄ that can be obtained on mixing 0.5 mol BaCl₂ with 1 mol H₂SO₄ is

0.5 mol

0.1 mol

0.15 mol

0.2 mol

Empirical formula of a hydrocarbon containing 85.71% carbon is:

CH₄

CH₂

CH₃

If isotopic distribution of ¹²C and ¹⁴C is 98.0% and 2.0%, respectively, then the number of ¹⁴C atoms in 12 g of carbon is:

1.032 × 10²²

1.20 × 10²²

5.88 × 10²³

6.02 × 10²³

Number of atoms present in 16 amu of He is;

4 NA

NA/4

How many molecules does 1 mole of carbon dioxide contain?

2NA

5NA

3NA

When 60 g of salt is dissolved in 600 mL of water, the mass by volume percentage of salt in the solution is:

66.6%

70%

10%

50%

The number of atoms in 20 g of SO₃ is approximately -

1 × 10²³

1.5 × 10²³

2 × 10²³

6 × 10²³

Given below are two statements: Statement-I: Atoms are neither created nor destroyed in a chemical reaction. Statement-II: Compounds are formed when atoms of different elements combine in a fixed ratio.

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

The mass percentage of carbon in ethanol (C₂H₅OH) is:

34.25%

52.17%

73.71%

46.26%

Given below are two statements: one is labelled as Assertion (A) and other is labelled as Reason (R):

Assertion (A): 2 moles of N₂ on reaction with 9 moles of H₂ will produce 4 moles of NH₃.

Reason (R): H₂ is a limiting reagent. In the light of above statements, choose the correct answer from the options given below:

A is true but R is false

A is false but R is true

Both A and R are true and R is the correct explanation of A.

Both A and R are true and R is NOT the correct explanation of A

80 g of oxygen gas contains as many atoms as in;

10 g of hydrogen gas

5 g of hydrogen gas

80 g of hydrogen gas

1 g of hydrogen gas

The number of ions present in 2 L of a solution of 1.6 M Al₂(SO₄)₃ is; [Given: N_A = 6 × 10²³ ]

4.8 × 10²²

4.8 × 10²³

9.6 × 10²⁴

9.6 × 10²²

25.3 g of sodium carbonate, Na₂CO₃ is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na⁺ and carbonate ions, CO₃^2– are respectively (Molar mass of Na₂CO₃ = 106 g mol^–1)

0.477 M and 0.477 M

0.955 M and 1.910 M

1.910 M and 0.955 M

1.90 M and 1.910 M

A molal solution is the one that contains one mole of a solute in:

1000 g of the solvent

one litre of the solvent

one litre of the solution

100 g of the solvent

20 g of metal combines with oxygen to form 60 g of metal oxide (MO). The percentage of oxygen in metal oxide is:

84.3%

72.9%

33.3%

66.6%

Compounds A, B and C have same empirical formula CH3. If molecular formula of compound – A, B and C is x, y and z respectively then select correct statements. A. x may be (CH3)2 B. z may be (CH3)1.5 C. y may be (CH3)5

A and B only

Only C only

C and B only

A and C only

Formula mass is used instead of molecular mass for:

O₂

NaCl

H₂O

One gram molecule of benzene is equal to;

10 g C6H6

70 g C6H6

72 g C6H6

78 g C6H6

2.4 g of Mg is burnt with 3.2 g of O₂ in a closed vessel. The amount of MgO formed is:[Atomic mass of Mg = 24 u, O = 16 u]

Mg + $\frac{1}{2}$ O₂→ MgO

0.1 mole

0.2 mole

0.05 mole

0.5 mole

Common salt obtained from sea-water contains 95% NaCl by mass. The approximate number of molecules present in 10 g salt is;

10²¹

10²²

10²³

10²⁴

Number of moles present in 3.6 g of a gas having vapour density 18 is:

0.02

0.1

0.2

0.01

x g of propane (C₃H₈) on combustion with 32 g of oxygen produces 26.4 g of CO₂ and 14.4 g of H₂O. The value of x is:

7.5 g

6.3 g

4.9 g

8.8 g

Avogadro’s number is the number of molecules present in

1 g of molecule

1 atom of molecule

gram molecular mass

1 Litre of molecule

4 moles of SO₂ and 6 moles of O₂ react to form SO₃. Total number of moles of reactant and product in the container when only 70% SO₂ is used is;

5.5

8.6

10.5

6.9

Which one contains the maximum number of molecules?

2 mol of N₂

41 g of dinitrogen

6.022 × 10²⁴ molecules

5 g atom of N₂

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion (A): Molality and mole fraction concentration units do not change with temperature. Reason (R): The concentration terms, molality and mole fraction do not involve volume terms.

A is true but R is false.

A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Both A and R are true but R is NOT the correct explanation of A.

The molecular formula of a compound is C₆H₁₂O₆. What’s the empirical formula?

C₂H₂O

CHO

C₂H₆O₂

CH₂O

92g of a compound on analysis gave 24g C, 4g H and 64g O. The empirical formula of compound is;

C₂H₄O₂

C₂H₂O₂

CH₂O₂

CH₂O

How many moles of potassium chlorate to be heated to produce 11.2 litre oxygen

0.5 mol

0.33 mol

0.25 mol

0.66 mol

Given below are two statements:

Assertion (A): 2 moles of N₂ on reaction with 9 moles of H₂ will produce 4 moles of NH₃.

Reason (R): H₂ is a limiting reagent.

In the light of above statements, choose the correct answer from the options given below:

A is true but R is false.

A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Both A and R are true and R is NOT the correct explanation of A.

The value of 40°C in Fahrenheit scale will be:

40°F

98°F

100°F

104°F

8 litre of H₂ and 6 litre of Cl₂ are allowed to react to maximum possible extent. Find out the final volume of reaction mixture. Suppose P and T remains constant throughout the course of reaction

7 litre

14 litre

2 litre

None of these

8 g NaOH is dissolved in one litre of solution, its molarity is:

0.8 M

0.4 M

0.2 M

0.1 M

For which of the following reactions Gay-Lussac’s law is not valid?

PCl₅(g)→ PCl₃(g) + Cl₂(g)

H₂(g) + Cl₂(g) → 2HCl(g)

2SO₂(g) + O₂(g) → 2SO₃(g)

2KClO₃(s) → 2KCl(s) + 3O₂(g)

Find the number of atoms present in 1.6 g of methane:

0.5 N_A

0.005 N_A

N_A

1.6 N_A

Given below are two statements: Statement-I: Avogadro’s number is a dimensionless quantity. Statement-II: Avogadro’s number is equal to the number of atoms or molecules in one gram mole.

Statement-I and Statement-II both are correct.

Statement-I is correct but Statement-II is incorrect.

Statement-I is incorrect but Statement-II is correct.

Statement-I and Statement-II both are incorrect.

The molarity of 20% (W/W) solution of sulphuric acid is 2.55 M. The density of the solution is

1.25 g cm^–3

0.125 g L^–1

2.55 g cm^–3

none of the above

Calculate the weight of lime (CaO) obtained by heating 200 kg of 95% pure lime stone (CaCO₃).

104.4 kg

105.4 kg

212.8 kg

106.4 kg

Given below are two statements: Statement-I: 1 mole H2SO4 contains same mass of oxygen and sulphur. Statement-II: 1 mole H2SO4 represents 98 g mass.

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

Mass of one molecule of methane (CH₄) is:

16 g

16 mg

16 u

16 N_A u

Which of the following alkanes has 75% of carbon?

C₂H₆

CH₄

C₃H₈

C₄H₁₀

Given below are two statements: Statement-I: Average atomic mass of chlorine is fractional. Statement-II: Average atomic mass is calculated by using natural abundances of different isotopes.

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

The number of significant figures for the three measurements 161 cm, 0.161 cm, 0.0161 cm are respectively

3, 4 and 5

3, 4 and 4

3, 3 and 4

3, 3 and 3

Which of the following law states that, “a given compound always contains exactly the same proportion of elements by weight”?

Avogadro

Definite proportions

Multiple proportions

Gay-Lussac

Which of the following concentration term is temperature dependent?

Mole fraction

Weight percentage

Molality

Molarity

The correct scientific notation for 0.0000212 is:

0.212 × 10^-6

2.12 × 10^-5

2.12 × 10⁴

2.12 × 10⁵

The maximum number of atoms are present in:

16 g of O₂

16 g of O₃

16 g of atomic oxygen

32 g of O₂

The prefix for multiple 10⁻¹² is;

giga

pico

kilo

mega

The molarity of solution containing 9.8 g of H₂SO₄ in 500 mL solution is:

0.2 M

2 M

0.5 M

5 M

Given below are two statements:

Statement I: Mass of 1 mole of oxygen gas is more than 1 mole nitrogen gas.

Statement II: 2 mole nitrogen gas occupies more volume than oxygen at STP.

In the light of the above statements, choose the correct answer from the options given below:

Both Statement I and Statement II are correct.

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are incorrect.

A quantity of 2.0 g of a triatomic gaseous element was found to occupy a volume of 448 ml at 76 cm of Hg and 273 K. The mass of its each atom is:

100 amu

5.53 × 10^-23 g

33.3 g

5.53 amu

One mole of CO₂ contains:

3 g atoms of CO₂

1.8 × 10²³ molecules

6.022 × 10²³atoms of O

6.022 × 10²³ atoms of C

The moles of O₂ required for reacting with 6.8 g of ammonia is:

4NH₃ + 5O₂ → 4NO + 6H₂O

2.5

0.5

The simplest formula of the compound containing 50% X (atomic mass 10 amu) and 50% Y (atomic mass 20 amu) is;

XY₂

X₂Y

X₂Y₃

XY₃

x g of propane (C₃H₈) on combustion with 32 g of oxygen produces 26.4 g of CO₂ and 14.4 g of H₂O. The value of x is:

7.5 g

6.3 g

4.9

8.8 g

5.85 g NaCl is dissolved in 1 L water. The total number of Na⁺ and Cl^– ions in 1 mL of this solution will be;

6.02 × 10¹⁹

1.2 × 10²²

1.2 × 10²⁰

6.02 × 10²⁰

How many moles of electron weigh one kilogram?

6.022 × 10^23

(1 × 10^31)/9.1

(6.022 × 10^54)/9.1

(1 × 10^8)/(9.1 × 6.022)

The statement which correctly represents Avogadro’s hypothesis is:

atoms of different elements may combine with each other in a fixed, simple, whole number ratio to form compounds.

equal volumes of all gases under the same temperature and pressure conditions contain an equal number of atoms.

equal volumes of all gases under the same conditions of temperature and pressure contain an equal number of molecules.

gases react together in volumes which bear a simple ratio to one another.

The percentage of nitrogen in urea (NH₂CONH₂), is;

38.4 %

46.6 %

59.1 %

61.3 %

What are the multiples for pico and deci respectively?

10^-12 and 10^-1

10^-9 and 10^-15

10^-15 and 10^-24

10^-12 and 10^-2

For a reaction,
N₂(g) + 3H₂(g) → 2NH₃(g)
Identify dihydrogen (H₂) as a limiting reagent in the following reaction mixtures:

14 g of N₂ + 4 g of H₂

28 g of N₂ + 7 g of H₂

56 g of N₂ + 10 g of H₂

35 g of N₂ + 8 g of H₂

The number of water molecules is maximum in

1.8 moles of water

1.8 g of water

18 g of water

18 moles of water

The ratio of total number of electrons present in 48 g of O₃ to 24 g of O₂ is

1 : 3

2 : 3

3 : 2

2 : 1

The mass of 1 × 10²³ molecules of H₂O is:

2.4 g

1.5 g

3 g

4.5 g

Given below are two statements:

Statement-I: 1g O₂ and 1g O₃ have equal number of atoms.

Statement-II: Mass of 1 mole of an atom is equal to its gram-atomic mass.

Statement I is correct but Statement II is incorrect.

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Both Statement I and Statement II are incorrect.

With increase of temperature, which of these changes?

Molality

Weight fraction of solute

Molarity

Mole fraction

The volumes of hydrogen & oxygen when combined to form H2O bear a simple ratio of 2:1. This is explained by;

Law of Multiple Proportions

Avogadro’s Law

Law of Definite Proportion

Gay Lussac’s Law of Gaseous Volumes

How much volume of oxygen will be required for complete combustion of 40 mL of acetylene (C₂H₂)? (All volume are measured at STP)

2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O

100 mL

80 mL

40 mL

200 mL

One atomic mass unit is defined as a mass exactly equal to:

one twelfth of the mass of one carbon-14 atom.

one twelfth of the mass of one carbon-12 atom.

one sixth of the mass of one carbon-12 atom.

one twelfth of the mass of one carbon-13 atom.

20 g of metal combines with oxygen to form 60 g of metal oxide (MO). The percentage of oxygen in metal oxide is

84.3%

72.9%

33.3%

66.6%

1 amu is equal to:

1.66056 × 10^-24 g

1.66056 × 10^-27 g

1.66056 × 10^-23 g

1.66056 × 10^-26 g

100

A measured temperature on Fahrenheit scale is 200°F. What will this reading be on the Celsius scale?

40°

91.5°

93.3°

30°

101

A mixture of gases contains H2 and O2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of two gases in the mixture?

1 : 2

4 : 1

2 : 2

2 : 3

102

The law of multiple proportions is illustrated by the pair of compounds;

NaCl and NaBr

H₂O and D₂O

SO₂ and SO₃

Mg(OH)₂ and MgO

103

An element, X has the following isotopic composition: 200X:90%, 199X:8.0%, 202X:2.0% The weighted average atomic mass of the naturally occurring element X is closest to

201 u

202 u

199 u

199.96 u

104

Scientific notation for the number 0.0001345 is

1.345 × 10⁻⁴

1.345 × 10⁻⁵

1.345 × 10⁻³

1.345 × 10⁻⁶

105

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion (A): One amu is equal to 1.66 × 10⁻²⁷ kg. Reason (R): One amu is the actual mass of one atom of C–12.

A is true but R is false.

A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Both A and R are true but R is NOT the correct explanation of A.

106

Given below are two statements:

Statement I: 10 ppm means 10 g solute in 10⁶ g solution.

Statement II: 1 m NaOH means 1 mol of NaOH is present in 1000 g solution.

Both correct

I correct II incorrect

I incorrect II correct

Both incorrect

107

Naturally occurring chlorine is 75 % Cl³⁵ and 25 % Cl³⁷. Calculate the average atomic mass of chlorine

35.5 amu

36.5 amu

71 amu

72 amu

Question Palette

Unattempted

Correct

Incorrect

List I

List II

Vapour density

2N_A atoms

1 mole

0.5 mole electrons

24 g carbon

iii

Collection of N_Aparticles

3.01 × 10²³

Molecular Mass × $\frac{1}{2}$