PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions for Chemistry

Name the reagent used in the following reaction:

Benzyl alcohol to benzoic acid.

When 3-methylbutan-2-ol is treated with HBr, the following reaction takes place:

\[\begin{array}{cc}
\phantom{.......................}\ce{Br}\\
\phantom{......................}|\\
\ce{CH3 - CH - CH - CH3 ->[HBr] CH3 - C - CH2 - CH3}\\
\phantom{.}|\phantom{......}|\phantom{......................}|\phantom{........}\\
\phantom{}\ce{CH3}\phantom{...}\ce{OH}\phantom{...................}\ce{CH3}\phantom{.....}
\end{array}\]

Give a mechanism for this reaction.

(Hint: The secondary carbocation formed in step II rearranges to a more

stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.)

Predict all the alkenes that would be formed by dehydrohalogenation of the following halide with sodium ethoxide in ethanol and identify the major alkene:

1-Bromo-1-methylcyclohexane

Predict all the alkenes that would be formed by dehydrohalogenation of the following halide with sodium ethoxide in ethanol and identify the major alkene:

2-Chloro-2-methylbutane

Predict all the alkenes that would be formed by dehydrohalogenation of the following halide with sodium ethoxide in ethanol and identify the major alkene:

2, 2, 3-Trimethyl-3-bromopentane

How will you bring about the following conversion?

But-1-ene to but-2-ene

Write the structure of the major organic product in the following reaction:

\[\ce{(CH3)3CBr + KOH ->[ethanol][heat]}\]

How the following conversion can be carried out?

1-Bromopropane to 2-bromopropane

How the following conversion can be carried out?

2-Chloropropane to 1-propanol

How the following conversion can be carried out?

2-Bromopropane to 1-bromopropane

What happens when PCl₅ is heated?

Write a balanced equation for the hydrolytic reaction of PCl₅ in heavy water.

Can PCl₅ act as an oxidising as well as a reducing agent? Justify.

Give an example of the reaction in the following case.

Oxime

Give an example of the reaction in the following case.

Imine

Define “Molar conductivity”.

State Kohlrausch’s law of independent migration of ions.

The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm⁻¹. Calculate its molar conductivity.

Why is bithional added to soap?

Give reasons for the following:

(i) Bond enthalpy of F₂ is lower than that of Cl₂.

(ii) PH₃ has lower boiling point than NH₃.