Free NEET Chemistry MCQs – NTA Syllabus Practice
Free NEET Chemistry MCQs | MCQAdda — Practice Questions
1. Which of the following species has the highest bond order?
- (A) O₂
- (B) O₂⁺
- (C) O₂⁻
- (D) O₂²⁻
Answer: (B) O₂⁺
Removal of one electron from the antibonding orbital of O₂ increases the bond order from 2 to 2.5.
2. Which of the following compounds exhibits the highest boiling point?
- (A) n-Pentane
- (B) Isopentane
- (C) Neopentane
- (D) Cyclopentane
Answer: (D) Cyclopentane
Cyclopentane has stronger intermolecular forces due to its cyclic structure, resulting in the highest boiling point.
3. The incorrect statement regarding SN1 reactions is:
- (A) Carbocation is formed as an intermediate.
- (B) Polar protic solvents favor the reaction.
- (C) Reaction rate depends only on substrate concentration.
- (D) Strong nucleophile is essential for the reaction.
Answer: (D) Strong nucleophile is essential for the reaction.
SN1 reactions depend mainly on carbocation stability and solvent polarity, not on nucleophile strength.
4. Which compound gives both Tollen's test and Fehling's test?
- (A) Benzaldehyde
- (B) Acetaldehyde
- (C) Acetone
- (D) Benzoic acid
Answer: (B) Acetaldehyde
Aliphatic aldehydes reduce both Tollen's and Fehling's reagents, whereas aromatic aldehydes generally do not reduce Fehling's solution.
5. Which oxide is amphoteric?
- (A) MgO
- (B) Na₂O
- (C) Al₂O₃
- (D) SO₃
Answer: (C) Al₂O₃
Aluminium oxide reacts with both acids and bases, showing amphoteric behavior.
6. Which of the following has the highest hydration enthalpy?
- (A) Li⁺
- (B) Na⁺
- (C) K⁺
- (D) Rb⁺
Answer: (A) Li⁺
Hydration enthalpy increases with decreasing ionic radius. Lithium ion is the smallest among the alkali metal ions.
7. Which complex exhibits tetrahedral geometry?
- (A) [Ni(CN)₄]²⁻
- (B) [PtCl₄]²⁻
- (C) [ZnCl₄]²⁻
- (D) [Pd(NH₃)₄]²⁺
Answer: (C) [ZnCl₄]²⁻
Zinc(II) with chloride ligands forms a tetrahedral complex, whereas the others are square planar.
8. Which of the following is paramagnetic?
- (A) CO
- (B) NO
- (C) CN⁻
- (D) N₂
Answer: (B) NO
NO contains one unpaired electron and is therefore paramagnetic.
9. For an exothermic reaction at equilibrium, increasing temperature will:
- (A) Increase K
- (B) Shift equilibrium toward products
- (C) Shift equilibrium toward reactants
- (D) Have no effect on equilibrium
Answer: (C) Shift equilibrium toward reactants
According to Le Chatelier's principle, increasing temperature favors the endothermic (reverse) direction.
10. Which of the following has the highest first ionization enthalpy?
- (A) Na
- (B) Mg
- (C) Al
- (D) Si
Answer: (B) Mg
Magnesium has a completely filled 3s² subshell, making electron removal more difficult than from aluminium.
11. Which compound will show optical isomerism?
- (A) 2-Propanol
- (B) 2-Butanol
- (C) Ethanol
- (D) Acetone
Answer: (B) 2-Butanol
2-Butanol contains one asymmetric carbon atom and therefore exhibits optical isomerism.
12. Which statement is correct for an ideal solution?
- (A) ΔHmix ≠ 0
- (B) ΔVmix ≠ 0
- (C) ΔHmix = 0 and ΔVmix = 0
- (D) Raoult's law is not obeyed
Answer: (C) ΔHmix = 0 and ΔVmix = 0
Ideal solutions obey Raoult's law over the entire composition range with no enthalpy or volume change on mixing.
13. Which of the following molecules has the highest dipole moment?
- (A) BF₃
- (B) CO₂
- (C) NH₃
- (D) CCl₄
Answer: (C) NH₃
NH₃ has a trigonal pyramidal geometry with a net dipole moment, while the others are symmetrical.
14. Which of the following is the strongest reducing agent in aqueous solution?
- (A) Li
- (B) Na
- (C) K
- (D) Cs
Answer: (A) Li
Lithium has the most negative standard reduction potential, making it the strongest reducing agent in aqueous solution.
15. Which of the following gives the iodoform test?
- (A) Methanal
- (B) Ethanal
- (C) Propanal
- (D) Benzaldehyde
Answer: (B) Ethanal
Ethanal is the only aldehyde containing the CH₃CO– group required for the iodoform reaction.
16. The coordination number of cobalt in [Co(NH₃)₆]Cl₃ is:
- (A) 3
- (B) 4
- (C) 6
- (D) 8
Answer: (C) 6
Six ammonia molecules are directly bonded to cobalt, giving a coordination number of six.
17. Which gas is liberated when zinc reacts with dilute hydrochloric acid?
- (A) Oxygen
- (B) Hydrogen
- (C) Chlorine
- (D) Carbon dioxide
Answer: (B) Hydrogen
Zinc reacts with dilute HCl to produce zinc chloride and hydrogen gas.
18. Which of the following exhibits maximum hydrogen bonding?
- (A) NH₃
- (B) HF
- (C) H₂O
- (D) CH₃OH
Answer: (C) H₂O
Water forms an extensive three-dimensional hydrogen-bonding network.
19. The rate constant of a first-order reaction has the unit:
- (A) mol L⁻¹ s⁻¹
- (B) s⁻¹
- (C) L mol⁻¹ s⁻¹
- (D) mol² L⁻² s⁻¹
Answer: (B) s⁻¹
The unit of a first-order rate constant is reciprocal time.
20. Which statement about catalysts is correct?
- (A) They change the equilibrium constant.
- (B) They increase the activation energy.
- (C) They provide an alternative reaction pathway with lower activation energy.
- (D) They shift the equilibrium toward products.
Answer: (C) They provide an alternative reaction pathway with lower activation energy.
Catalysts lower the activation energy and increase the reaction rate without affecting the equilibrium position or equilibrium constant.