The pK_a values of four carboxylic acids are given below. Identify the weakest carboxylic acid.

• 4.89

• 1.28

• 4.76

• 2.56

Which one of the following is an example of disproportionation reaction?

• 3Cl₂ (g) + 6OH^- (aq) → ClO${}_3^{-}$ (aq) + 5Cl^- (aq) + 3H₂O (l)

• Ag²⁺ (aq) + Ag (s) → 2Ag⁺ (aq)

• Zn (s) + CuSO₄ (aq) → Cu (s) + ZnSO₄ (aq)

• 2KClO₃ (s) → 2KCl (s) + 3O₂ (g)

Observe the following statements-

i. Heavy water is harmful for the growth of animals.

ii. Haevy water reacts with Al₄C₃ and forms deyterated acetylene. 

iii. BaCl₂.2D₂O is an example of interstitial deuterate.

The correct statements are-

• 1 and 3

• 1 and 2

• 1, 2 and 3

• 2 and 3

Diborane reacts with HCl in the presence of AlCl₃ and liberates

• H₂

• Cl₂

• BCl₃

• Cl₂ and BCl₃

How many corners of SiO₄ units are shared in the formation of three dimensional silicates?

• 3

• 2

• 4

• 1

Na₂S₂O₃ reacts with moist Cl₂ to form Na₂SO₄, HCl and X. Which one of the following is X?

• H₂S

• SO₂

• SO₃

• S

Cataract and skin cancer are caused by

• depletion of nitric oxide

• depletion of ozone layer

• increase in methane

• depletion of nitrous oxide

C₂H₆ $\stackrel{450°\mathrm{C}}{\to }$ C₂H₄ + H₂

Above reaction is known as

• combustion

• rearrangement

• pyrolysis

• cleavage

19.

Assertion (A) : NH₂ group of aniline is ortho, para directing in electrophilic substitutions.

Reason (R) : -NH₂ group stabilises the arenium ion formed by the ortho, para attack of the electrophile.

The correct answer is

• Both (A) and (R) are correct, (R) is the correct explanation of (A).

• Both (A) and (R) are correct, (R) is not the correct explanation of (A).

• (A) is correct, but (R) is not correct.

• (A) is not correct, but (R) is correct.

In which of the following properties, the two enantiomers of lactic acid differ from each other?

• Sign of specific rotation

• Density

• Melting point

• Refractive index