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JEE • CHEMISTRY • SOME BASIC CONCEPTS OF CHEMISTRY

Some basic concepts of chemistry practice · Mixed difficulty

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 1-30 of 436 questions

1 Easy

1 of 436

Application +4 | -1

If a mixture containing 3 moles of hydrogen and 1 mole of nitrogen is converted completely into ammonia, the ratio of initial and final volumes under the same temperature and pressure would be:

View answer and explanation

Correct option: C

2\mathrm{ }:\mathrm{ }1

Option C (2 : 1) is correct because the ratio of initial to final volumes is determined by the stoichiometry of the reaction and the number of moles of reactants and products.

2 Easy

2 of 436

Remembering +4 | -1

How many g are present in one mole of Ag?

View answer and explanation

Correct option: A

107.9

Option A (107.9) is correct because the molar mass of Ag (Silver) is approximately 107.9 g/mol.

3 Hard

3 of 436

Application +4 | -1

8 g of NaOH is dissolved in 18 g of

{H_2}O.

Mole fraction of NaOH in solution and molality (in

mol\,\,k{g^{ - 1}})

of the solution respectively are

View answer and explanation

Correct option: D

0.167, 11.11

Option D (0.167, 11.11) is correct because it accurately calculates the mole fraction of NaOH and the molality of the solution.

4 Easy

4 of 436

Application +4 | -1

2.24 {~L}

{CH}_4

at NTP contains :-

View answer and explanation

Correct option: D

Both (2) and (3)

Option D (Both (2) and (3)) is correct because 2.24 L of

{CH}_4

at NTP contains

6.02 \times 10^{22}

molecules and

5 \times 6.02 \times 10^{22}

atoms.

5 Medium

5 of 436

Application +4 | -1

One litre of

{CO}_2

is passed through red hot coke. The volume becomes 1.4 litres at same temperature and pressure. The composition of products is

View answer and explanation

Correct option: C

0.6 litre of

{CO}_2

and 0.8 litre of

{CO}

Option C (0.6 litre of

{CO}_2

and 0.8 litre of

{CO}

) is correct because the reaction consumes some CO2 to produce CO, and the final volume is 1.4L.

6 Medium

6 of 436

Application +4 | -1

How many millilitre of

0.5 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4

are needed to dissolve

0.5 \mathrm{~g}

\mathrm{Cu}(\mathrm{II})

carbonate?

View answer and explanation

Correct option: C

8.1

Option C (8.1) is correct because it is calculated using the stoichiometry of the reaction between H2SO4 and CuCO3.

7 Easy

7 of 436

Application +4 | -1

Equivalent weight of a bivalent metal is 37.2. The molecular weight of its chloride is

View answer and explanation

Correct option: C

145.4

Option C (145.4) is correct because the molecular weight of the metal chloride is calculated from the equivalent weight of the bivalent metal.

8 Hard

8 of 436

Application +4 | -1

A sample of sodium has a mass of

46 \mathrm{~g}

. What is the mass of the same number of calcium atoms as sodium atoms present in given sample?

View answer and explanation

Correct option: D

80 \mathrm{~g}

Option D (

80 \mathrm{~g}

) is correct because the mass of the same number of calcium atoms is twice the mass of sodium atoms since the atomic mass of calcium is approximately twice that of sodium.

9 Medium

9 of 436

Understanding +4 | -1

Statement I: Chemical equivalent of

\mathrm{Mg}

is half of its atomic weight

Statement II: Charge present on

\mathrm{Mg}

is +2

View answer and explanation

Correct option: A

If both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

Option A (If both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I) is correct because the chemical equivalent of an element is its atomic weight divided by its valency, and the valency of Mg is 2.

10 Medium

10 of 436

Application +4 | -1

If the mass of neutron is doubled and that of proton is halved, the molecular mass of

\mathrm{H}_2 \mathrm{O}

containing only

\mathrm{H}^1

and

\mathrm{O}^{16}

atoms will

View answer and explanation

Correct option: C

Increase by about

16.67 \%

Option C (Increase by about 16.67 %) is correct because the new molecular mass of H2O increases from 18 to 21, which is approximately a 16.67% increase.

11 Easy

11 of 436

Understanding +4 | -1

Molar concentration of a solution in water is:

View answer and explanation

Correct option: B

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16 Hard

16 of 436

Application +4 | -1

The most abundant elements by mass in the body of a healthy human adult are Oxygen (61.4%); Carbon (22.9%), Hydrogen (10.0%); and Nitrogen (2.6%). The weight which a 75 kg person would gain if all

{}^1H

atoms are replaced by

{}^2H

atoms is

View answer and explanation

Correct option: C

7.5 kg

Option C (7.5 kg) is correct because it is the mass gain calculated by replacing all

{}^1H

atoms with

{}^2H

atoms.

17 Medium

17 of 436

Understanding +4 | -1

Which term is to be correctly used for expressing concentration of electrolytes in solution?

View answer and explanation

Correct option: C

Formality

Option C (Formality) is correct because formality is specifically used to express the concentration of electrolytes in solution, accounting for their dissociation.

18 Medium

18 of 436

Analyzing +4 | -1

A: One mole of sucrose reacts completely with oxygen produces 268.8 litre of carbon dioxide at STP.

R: Amount of oxygen required for reaction is 268.8 litre.

View answer and explanation

Correct option: B

Both A and R are correct, but R is not the correct explanation of A.

Both the assertion and the reason are correct, but the reason is not the correct explanation of the assertion. The amount of CO2 produced and O2 required are both 268.8 L, but the production of CO2 is not *caused* by the amount of oxygen required.

19 Medium

19 of 436

Application +4 | -1

What is the equivalent weight of

{ClO}_3^{-}

in the following reaction?

{ClO}_3^{-}+{Fe}^{2+}+{H}^{+} \longrightarrow {Cl}^{-}+{Fe}^{3+}+{H}_2 {O}

View answer and explanation

Correct option: A

13.9167

Option A (13.9167) is correct because it is the equivalent weight of ClO₃⁻ calculated based on the change in oxidation state of chlorine.

20 Medium

20 of 436

Understanding +4 | -1

The equivalent weight of an acid is obtained by dividing its mol. wt. by its:

View answer and explanation

Correct option: B

Basicity

Option B is correct because the equivalent weight of an acid is determined by dividing its molecular weight by its basicity (number of replaceable hydrogen ions).

21 Easy

21 of 436

Understanding +4 | -1

Assertion: Atomicity of phosphorus is four.
Reason: Atomicity is the number of atoms present in 1 molecule.

View answer and explanation

Correct option: C

Both Assertion and Reason are correct and Reason is correct explanation of Assertion

Option C is correct because the assertion that the atomicity of phosphorus is four is correct, and the reason correctly explains what atomicity means.

22 Hard

22 of 436

Application +4 | -1

50 \mathrm{~mL}

0.01 \mathrm{~M} \mathrm{~FeSO}_4

will react with what volume of

0.01 \mathrm{~M} \mathrm{~KMnO}_4

solution in acid medium?

\left(1 \mathrm{~mol} \mathrm{~KMnO}_4\right.

requires

5 \mathrm{~mol}

\mathrm{FeSO}_4

for complete reaction)

View answer and explanation

Correct option: D

10 \mathrm{~mL}

Option D (

10 \mathrm{~mL}

) is correct because the volume of KMnO4 required is calculated using the stoichiometry of the reaction.

23 Medium

23 of 436

Application +4 | -1

The no. of moles of Hydrogen molecules required to produce 20 moles of

N{H_3}

through Haber’s process is

View answer and explanation

Correct option: B

Option B (30) is correct because the balanced equation for Haber's process shows that 3 moles of H2 are required for every 2 moles of NH3.

24 Medium

24 of 436

Application +4 | -1

The number of electrons in

2 \mathrm{~g}

ion of nitrate ion

\left(\mathrm{NO}_3^{-}\right)

View answer and explanation

Correct option: B

64 N_{\mathrm{A}}

Option B (

64 N_{\mathrm{A}}

) is correct because the total number of electrons is calculated by multiplying the number of nitrate ions by the number of electrons per nitrate ion.

25 Medium

25 of 436

Understanding +4 | -1

Irrespective of the source, pure sample, of water always yields 88.89% mass of oxygen and 11.11% mass of hydrogen. This is explained by the law of

View answer and explanation

Correct option: C

constant composition

The correct answer is C (constant composition) because the fixed mass ratio of oxygen and hydrogen in water, regardless of its source, exemplifies the law of constant composition.

26 Medium

26 of 436

Application +4 | -1

One molecule of haemoglobin will combine with four molecules of oxygen. If

1.0 \mathrm{~g}

of haemoglobin combines with

1.642 \mathrm{~ml}

of oxygen at body temperature

\left(27^{\circ} \mathrm{C}\right)

and a pressure of 760 torr, then what is the molar mass of haemoglobin?

View answer and explanation

Correct option: D

60,000

Option D (60,000) is correct because the molar mass of hemoglobin is calculated using the ideal gas law and the stoichiometry of oxygen binding to hemoglobin.

27 Medium

27 of 436

Application +4 | -1

6.02 \times 10^{20}

molecules of urea are present in

200 \mathrm{~mL}

of its solution. The concentration of urea solution is

View answer and explanation

Correct option: C

0.005 \mathrm{~M}

Option C (

0.005 \mathrm{~M}

) is correct because the concentration is calculated by dividing the number of moles of urea by the volume of the solution in liters.

28 Medium

28 of 436

Application +4 | -1

The mass of

1.5 \times 10^{20}

molecules of a substance is

20 \mathrm{~mg}

. The molar mass of the substance is

View answer and explanation

Correct option: C

80 \mathrm{~g}

Option C (

80 \mathrm{~g}

) is correct because it is the molar mass calculated from the given number of molecules and mass of the substance.

29 Medium

29 of 436

Analyzing +4 | -1

In the reaction of oxalate with permanganate in acidic medium. The number of electrons involved in producing one molecule of

C{O_2}

View answer and explanation

Correct option: C

Option C is correct because the oxidation of one oxalate ion to two CO2 molecules involves a transfer of 2 electrons, meaning 1 electron per CO2 molecule.

30 Medium

30 of 436

Application +4 | -1

Manganese forms non-stoichiometric oxides having the general formula

\mathrm{MnO}_x

. The value of

x

for the compound that analyzed

64 \%

by mass

\mathrm{Mn}

View answer and explanation

Correct option: D

1.93

Option D (1.93) is correct because the value of x is calculated using the given mass percentage of Mn in the non-stoichiometric oxide.

Revision notes and key takeaways

Review SOME BASIC CONCEPTS OF CHEMISTRY in your textbook or class notes, then use this set to check your understanding.

Key Takeaways

✓ This set contains 436 single-correct-answer MCQs on SOME BASIC CONCEPTS OF CHEMISTRY.
✓ Try each question before opening its answer. Read the explanation where one is available.
✓ Sign in to save submitted answers. Revisit incorrect answers alongside your textbook or class notes.

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