Neet 2019 Chemistry Question (1-15)

 

NEET 2019 Chemistry – Question 1 to 15

Q1. Which of the following compounds shows metamerism?

A. CH₃CH₂OCH₂CH₃
B. CH₃COCH₃
C. CH₃CH₂CH₂OH
D. CH₃CH₂COOH

Answer: A

Explanation: Metamerism is shown by ethers due to different alkyl groups on either side of oxygen.

Metamers have same molecular formula but different alkyl groups around the functional group.

Q2. Which of the following elements is not a d-block element?

A. Fe
B. Cu
C. Zn
D. La

Answer: D

Explanation: La (Lanthanum) is an f-block element (lanthanide series).

d-block elements are transition metals, whereas lanthanides belong to f-block.

Q3. Which of the following compounds is most acidic?

A. CH₃CH₂OH
B. C₆H₅OH
C. CH₃COOH
D. CH₃OH

Answer: C

Explanation: Carboxylic acid (CH₃COOH) is more acidic due to resonance stabilization of carboxylate ion.

Acidity increases with better anion stabilization after proton removal.

Q4. The major product of the reaction CH₃CH=CH₂ + HBr (in presence of peroxide) is:

A. CH₃CHBrCH₃
B. CH₃CH₂CH₂Br
C. CH₂BrCH₂CH₃
D. CH₃CHBrCH₂

Answer: B

Explanation: In presence of peroxide, HBr adds via anti-Markovnikov rule forming CH₃CH₂CH₂Br.

Peroxide effect applies only with HBr, giving anti-Markovnikov product.

Q5. Which one of the following is a correct match?

A. XeF₂ – Linear geometry
B. SF₆ – Square planar
C. ClF₃ – Tetrahedral
D. NH₃ – Trigonal planar

Answer: A

Explanation: XeF₂ has linear geometry due to sp³d hybridization with 3 lone pairs.

Use VSEPR theory to predict shapes based on electron pairs.

Q6. Which of the following has maximum unpaired d-electrons?

A. Ti³⁺
B. Fe²⁺
C. Co³⁺
D. Cr³⁺

Answer: D

Explanation: Cr³⁺ has 3d³ configuration → 3 unpaired electrons (maximum here).

Count electrons from configuration after ionization.

Q7. Tyndall effect is shown by:

A. True solution
B. Colloidal solution
C. Suspension
D. None of these

Answer: B

Explanation: Tyndall effect is scattering of light by colloidal particles.

Only colloids show Tyndall effect due to particle size 1–1000 nm.

Q8. Which of the following has maximum number of atoms?

A. 1 g of Mg
B. 1 g of O₂
C. 1 g of Li
D. 1 g of Ag

Answer: C

Explanation: Li has lowest molar mass, hence more moles and atoms.

Atoms = (1 g / molar mass) × Avogadro number.

Q9. Which of the following is not a colligative property?

A. Osmotic pressure
B. Vapour pressure lowering
C. Boiling point elevation
D. Refractive index

Answer: D

Explanation: Refractive index is not a colligative property; it depends on nature, not number of solute particles.

Colligative properties depend only on the number of solute particles.

Q10. Which one is the strongest acid?

A. HCl
B. HNO₃
C. H₂SO₄
D. HClO₄

Answer: D

Explanation: HClO₄ is a strong acid due to resonance and electronegative oxygen atoms stabilizing the anion.

Acid strength increases with anion stability.

Q11. Which of the following has maximum bond angle?

A. NH₃
B. H₂O
C. CH₄
D. CO₂

Answer: D

Explanation: CO₂ is linear, bond angle = 180°, which is maximum.

Linear molecules have bond angles of 180°.

Q12. Which of the following is used in the preparation of colloids?

A. Peptization
B. Precipitation
C. Condensation
D. All of these

Answer: D

Explanation: All are methods to prepare colloids.

Colloids can be formed by various physical and chemical methods.

Q13. Which of the following is a Lewis base?

A. BF₃
B. NH₃
C. AlCl₃
D. H⁺

Answer: B

Explanation: NH₃ donates lone pair → Lewis base.

Lewis base = lone pair donor; Lewis acid = electron pair acceptor.

Q14. Which has highest boiling point?

A. H₂O
B. H₂S
C. H₂Se
D. H₂Te

Answer: A

Explanation: H₂O has strong hydrogen bonding, raising boiling point.

Hydrogen bonding increases boiling points significantly.

Q15. In which process is ∆G = 0?

A. Irreversible process
B. Spontaneous process
C. Equilibrium
D. None

Answer: C

Explanation: At equilibrium, the Gibbs free energy change is zero (∆G = 0).

∆G = 0 means system is at equilibrium — no net change occurs.