JEE Advanced 2023 Chemistry Sample Questions

1. Which of the following liberates O2 upon hydrolysis?

a) Pb3O4

b) KO2

c) Na2O2

d) Li2O2

Answer: (B), KO2 Superoxides liberate oxygen with water.

2. Aluminium reacts with sulfuric acid to form aluminium sulfate and hydrogen. What is the volume of hydrogen gas in litres (L) produced at 300 K and 1.0 atm pressure, when 5.4 g of aluminium and 50.0 mL of 5.0 M sulfuric acid are combined for the reaction?

(Use the molar mass of aluminum as 27.0 g mol−1, ???? = 0.082 atm L mol−1 K−1)

Answer: 2Al + 3H2SO4 → Al2(SO4)3 + 3H2

Mole of Al taken = 5.4 / 27 = 0.2

Mole of H2SO4 taken = 50 X 5 / 1000 = 0.25

As 0.2 / 2 > 0.25 / 3, H2SO4 is limiting reagent

Now, moles of H2 formed = 3 / 3 X 0.25 = 0.25

Therefore Volume = 0.25 x 0.082 x 300 / 1 = 24.6 / 4 = 6.15 L

3. Na and Mg crystallize in BCC and FCC type crystals respectively. Then the number of atoms of Na and Mg present in the unit cell of their respective crystal is (2002)
   1. 4 and 2
   2. 9 and 14
   3. 14 and 9
   4. 2 and 4

Answer: (D), no of atoms per unit cell= 8*1/8+6*1/2=4

4. How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00 g? (Atomic masses: Na = 23, Cl = 35.5)
   1. 5.14 x 1021 unit cell
   2. 1.28 x 1021 unit cell
   3. 1.71 x 1021 unit cell
   4. 2.57 x 1021 unit cell

Answer: (D), no of unit cell= 1.0*6.02*1023/58.5*4= 2.57*1021

5. Which one of the following statements is NOT true about the effect of an increase in temperature on the distribution of molecular speeds in a gas?

1. The most probable speed increases
2. The fraction of the molecules with the most probable speed increases
3. The distribution becomes broader
4. The area under the distribution curve remains the same as under the lower temperature

Answer: (B), most probable velocity increases and a fraction of the molecule possessing the most probable velocity decreases.

6. The formation of gas at the surface of tungsten due to adsorption is the reaction of order?
   1. 0
   2. 1
   3. 2
   4. 3

Answer: (A), it is a zero-order reaction.

7. The internal energy change when a system goes from state A to B is 40 kJ/mol-1 if the system goes from A to B by a reversible path and returns to state A by an irreversible path. What would be the net change in internal energy?
   1. > 40 kJ
   2. <40 kJ
   3. Zero
   4. 40 kJ

Answer: (C), for a cyclic process the net change in the internal energy is zero because the change in internal energy does not depend on the path.

Check JEE Advanced 2023 Practise Papers for more question papers