NEET WEEKLY TEST CHEMISTRY (20.09.2025)SDA

Q1. For a chemical process occurring at constant temperature and pressure, which of the following determines whether the process is spontaneous?

(a) ΔH only

(b) ΔS only

(c) ΔG

(d) Activation energy

Q2. Consider a reaction with ΔH = −40.0 kJ·mol⁻¹ and ΔS = −100.0 J·K⁻¹·mol⁻¹. At which temperature range will the reaction be spontaneous?

(a) At all temperatures

(b) At low temperatures only

(c) At high temperatures only

(d) Never spontaneous

Q3. For a reaction at equilibrium under given T and P, the Gibbs free energy change ΔG (for the reaction as written) is:

(a) ΔG < 0

(b) ΔG > 0

(c) ΔG = 0

(d) Cannot be determined without ΔH

Q4. The enthalpy of combustion of CH₄ is –890 kJ·mol⁻¹. What is the amount of heat released when 11.2 L of methane at STP is burnt completely?

(a) –445 kJ

(b) –222.5 kJ

(c) –1780 kJ

(d) –890 kJ

Q5. The entropy change ΔS_system is positive (i.e., increases) for which of the following processes (at the stated conditions)?

(a) Ice melting at 0 °C (fusion of ice)

(b) Water freezing at 0 °C

(c) Isothermal compression of an ideal gas

(d) Formation of NaCl(s) from Na(s) and ½Cl₂(g)

6. For the reaction 2H2(g) + O2(g) → 2H2O(l), ΔH = -572 kJ/mol. What is the enthalpy change for the formation of 1 mole of H2O?

A) -286 kJ/mol
B) -572 kJ/mol
C) +286 kJ/mol
D) +572 kJ/mol

8. According to Kirchhoff’s equation, ΔH2 – ΔH1 = ?

A) ΔCp(T2 – T1)
B) ΔCp(T2 + T1)
C) ΔCv(T2 – T1)
D) ΔCv(T2 + T1)
D) ΔCv(T2 + T1)

9. Given standard enthalpies of formation (ΔHf°):

ΔHf°(CH₄, g) = −74.8 kJ·mol⁻¹

ΔHf°(CO₂, g) = −393.5 kJ·mol⁻¹

ΔHf°(H₂O, l) = −285.8 kJ·mol⁻¹

Calculate ΔH for the reaction :

CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(l)

 

a) −965.1 kJ
b) −818.7 kJ
c) −890.3 kJ
d) −74.8 kJ

10. For a reaction: ΔH = +50.0 kJ·mol⁻¹ and ΔS = +80 J·mol⁻¹·K⁻¹.

Find the minimum temperature above which the reaction becomes spontaneous.

a) 100 K
b) 273 K
c) 625 K
d) 500 K

11. For a reaction, ΔG° = +10 kJ·mol⁻¹ at 298 K. Which of the following is correct?

 

a) Equilibrium constant K > 1
b) Equilibrium constant K < 1
c) Reaction will never proceed forward.
d) ΔH = 0

12. For the reaction:

H₂(g) + Cl₂(g) → 2HCl(g),

ΔH = −184.6 kJ at 298 K. What is ΔU? (R = 8.314 J·mol⁻¹·K⁻¹)

a) −184.6 kJ
b) −182.1 kJ
c) −187.1 kJ
d) −190.0 kJ

13. For a reaction, if ΔG° = 0, what can be concluded about the equilibrium constant (K)?

a) K = 1
b) K > 1
c) K < 1
d) No relation between ΔG° and K

14. For free expansion of an ideal gas in an isolated container:

a) ΔU = 0, q = 0, w = 0
b) ΔU ≠ 0, q = 0, w = 0
c) ΔU = 0, q ≠ 0, w = 0
d) ΔU ≠ 0, q ≠ 0, w ≠ 0

Given the following reactions and their enthalpy changes:

 

1. C(s) + O2(g) → CO2(g), ΔH = -393.5 kJ/mol
2. CO(g) + 1/2O2(g) → CO2(g), ΔH = -283.0 kJ/mol

 

15. What is the enthalpy change (ΔH) for the reaction:

C(s) + 1/2O2(g) → CO(g)?

 

A) -110.5 kJ/mol
B) +110.5 kJ/mol
C) -676.5 kJ/mol
D) +676.5 kJ/mol

19. The equilibrium constant, K for the reaction 2Hl(g) ⇋ H₂(g) + I₂(g) at room temperature is 2.85 and that at 698 K is 1.4 x 10^-2. This implies that the forward reaction is

1. exothermic
2. exergonic
3. endothermic
4. unpredictable

20. For a reversible reaction, the concentration of the reactants are doubled, then the equilibrium constant

1. becomes one-fourth
2. is doubled
3. is halved
4. remains same.

At a given temperature, the equilbrium constant for the reactions

NO(g) + 1/2O₂(g) ⇋NO₂(g) and

2NO₂(g) ⇋2NO + O₂(g)

are K1 and K2. If K1 is 4 x 10^-3, then K2 will be

1. 8 x 10^-3
2. 16 x 10^-3
3. 25 x 10⁴
4. 25 x 10⁶

22. The equilibrium constants for the reactions at 100K are

CoO(s) + H₂(g) ⇋Co(s) + H₂O(g); K1 = 65

CoO(s) + CO(g) ⇋Co(s) + CO₂(g); K2 = 500

The equilibrium constant for the reaction:

CO(g) + H2O(g) ⇋CO2(s) + H2(g)at 100K is

1. 0.13
2. 7.69
3. 0.0179
4. 69.3

23. The values of Kc for the following reactions are gives ad:

A ⇋B, Kc = 1, B ⇋C, Kc = 3 and C ⇋D, Kc = 5

Evaluate the value of Kc for A ⇋D

1. 15
2. 5
3. 3
4. 1

24. N2(g) + 3H2(g) ⇋2NH3(g)

For the reaction initially the mole ratio was 1:3 of N2:H2. At equilibrium 50% of each has reacted. If the equilibrium pressure was P, the partial pressure of NH3 at equilibrium was

1. P/3
2. P/4
3. P/6
4. P/8

25. At 550K, the Kc for the following reaction is 10⁴ mol^-1L

X(g) + Y(g) ⇋Z(g)

At equilibrium, it was observed that [X] = 1/2[Y] = 1/2 [Z]

What is the value of [Z] (in molL^-1) equilibrium?

1. 2 x 10^-4
2. 10^-4
3. 2 x 10⁴
4. 10⁴

26. 3O₂(g) ⇋2O₃(g)

For the above reaction at 298K. Kc is found to be 3.0 x 10^-59. If the concentration of O2 at equilibrium is 0.040M then concentration of O3 in M is

1.9 x 10^-63

2.4 x 10³¹

1.2 x 10²¹

4.38 x 10^-32

27. In which of the following equilibria, K_p and K_c are NOT equal?

1. PCl_5(g) ⇋PCl_3(g) + Cl_2(g)
2. H_2(g) + I_2(g) ⇋2HI_(g)
3. CO_(g) + H₂O_(g) ⇋CO_2(g) + H_2(g)
4. 2BrCl_(g) ⇋Br_2(g) + Cl_2(g)

29. The equilibrium between water and its vapour, in an open vessel

 

1. can be achieved
2. depends upon pressure
3. cannot be achieved
4. depends upon temperature

29. A reaction is said to be in equilibrium when

 

1. the rate of transformation of reactants to products is equal to the t=rate of transformation of products to the reactants
2. 50% of the reactants are converted to products
3. the reaction is near completion and all the reactants are converted to products
4. the volume of reactants is just equal to tthe volume of the products.

30. Which of the following is not true about a reversible reaction?

 

1. The reaction does not proceed to completion.
2. It cannot be influenced by a catalyst
3. Number of moles of reactants and products is always equal.
4. It can be attained only in a closed container.

31. Which of the following is a polar molecule?

 

1. SiF₄
2. XeF₆
3. BF₃
4. ZnCl₂

32. The number of lone pairs on Xe in XeF₆,XeF₄ and XeF₂ respectively are

 

1. 3, 2, 1
2. 2, 4, 6
3. 1, 2, 3
4. 6, 4, 2

33. Which of the following molecules/ions does not contain unpaired electrons?

 

1. N₂⁺
2. B₂
3. N₂
4. O₂

34. Which of the following has pπ-dπ bonding ?

 

1. CO
2. BO₃^2-

3. NO₃^–

4. PO₃^2-

35. Which of the following has minimum ionic character?

 

1. NaCl
2. KCl
3. CsCl
4. RbCl

36. Which one of the following molecules contains no π bond ?

 

1. CO₂
2. NH₃
3. HCN
4. Ethene

37. During the change of O₂ to O₂^–, the incoming electron goes to the orbital :

 

1. σ*2p_z
2. π*2p_x
3. π*2p_y
4. π2p_x

38. Which of the following pairs of ions are isoelectronics and isostructural ?

 

1. ClO₃^–, CO₃^2-
2. PCl₅, POCl₃
3. ClO₃^–, SO₃^2-
4. SF₆,ClF₃

39. Total number of lone pair of electrons on XeF₄ is ?

 

1. 1
2. 2
3. 3
4. 4

40. The following pair which contain polar molecule is

 

1. CCl₄ and CO₂
2. PF₅ and XeF₂
3. SiF₄ and  SbCl₅
4. BeCl₂ and SF₆

Which Hybridisation is not match with the following compound?

 

1. SO₄^2- – sp³
2. NH₄⁺ – sp³
3. BrF₅ – sp³d²
4. SF₆ – sp³d³

42. Which of the following has the lowest lattice energy ?

1. LiF
2. RbF
3. KF
4. NaF

43. Two pi and half sigma bonds are present in

 

1. N₂⁺
2. N₂
3. O₂
4. O₂⁺

44. Choose the incorrect about the d-orbitals used in different types of hybridizations

 

1. sp³d- d_x2-y2
2. sp³d² – d_x2-y2, d_z2
3. sp³d³ – d_xy, d_yz, d_zx
4. dsp² – d_x2-y2

45. On applying pressure to the equilibrium, H₂O(s) ⇋ H₂O(l) which phenomenon will happen?

 

1. More ice will be formed
2. More water will be formed
3. Equilibrium will not disturb
4. All of these are correct.