21.

Which of the following is a chiral compound?

• Hexane

• n-Butane

• Methane

• 2,3,4-Trimethylhexane.

MnO₃ in an acidic medium dissociates into

• ${\mathrm{MnO}}_2 \mathrm{and} {\mathrm{MnO}}_4^{-}$

• $\mathrm{MnO} \mathrm{and} {\mathrm{MnO}}_4^{-}$

• ${\mathrm{MnO}}_2 \mathrm{and} \mathrm{MnO}$

• ${\mathrm{MnO}}_2 \mathrm{and} {\mathrm{MnO}}_3$

Which of the following compounds are optically active?

• 1 and 2

• 2 and 3

• 3 and 4

• 1 and 4

Number of isomers of C₅H₆

• 2

• 3

• 4

• 5

Assertion : 1, 2-dichloroethane is optically active.

Reason : Meso compound is optically active.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : Phenol is more reactive than benzene towards electrophilic substitution reaction.

Reason : In the case of phenol, the intermediate carbocation is more resonance stabilised.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

How many P = 0 bond present in (HPO₃)₃?

• 0

• 3

• 6

• 9

In bcc structure contribution of comer and central atom is

• $\frac{1}{8},1$

• $\frac{1}{4},\frac{1}{8}$

• $\frac{1}{8},\frac{1}{2}$

• $\text{1,}\frac{1}{2}$

Which is not stable under ambient condition?

• ${\mathrm{TiO}}_{2, }{\mathrm{Ti}}^{+4}$

• $\mathrm{VO}, {\mathrm{V}}^{+4}$

• ${\mathrm{VO}}_{2, }{\mathrm{V}}^{+5}$

• ${\mathrm{Cu}}_2\mathrm{O}, {\mathrm{Cu}}^{+2}$

Which of the following is the correct statement for PH₃?

• It is less poisonous than NH₃.

• It is less basic than NH₃.

• Electronegativity of PH₃ >NH_3.

• It does not show reducing properties.