Science (English Medium) कक्षा १२ - CBSE Important Questions for Chemistry

Which would undergo S_N2 reaction faster in the following pair and why ?

Indicate the principle behind the method used for the refining of zinc.

Which form of the iron is the purest form of commercial iron?

Give reasons : n-Butyl bromide has higher boiling point than t-butyl bromide.

Give reasons : Racemic mixture is optically inactive.

The presence of nitro group (−NO₂) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions.

What is the principle behind the zone refining of metals?

Identify the chiral molecule in the following pair :

Explain the principle of the method of electrolytic refining of metals. Give one example.

Write the structures of A, B and C in the following:

p-Dichlorobenzene has higher m.p. and lower solubility than those of o- and m-isomers. Discuss.

Give reasons:

The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

Which reducing agent is employed to get copper from the leached low-grade copper ore?

Draw the structure of major monohalo product in each of the following reactions :

Arrange the following compounds in increasing order of their boiling points.

(a)  \[\begin{array}{cc}
\ce{CH3}\phantom{..................}\\
\backslash\phantom{...........}\\
\ce{CH - CH - CH2Br}\\
/\phantom{.............}\\
\ce{CH3}\phantom{..................}
\end{array}\]

(b) \[\ce{CH3CH2CH2CH2Br}\]

(c) \[\begin{array}{cc}
\phantom{...}\ce{CH3}\\
\phantom{}|\\
\ce{H3C - C - CH3}\\
\phantom{}|\\
\phantom{..}\ce{Br}
\end{array}\]

Arrange the following compounds in increasing order of their boiling points:

CH₃CH₂OH, CH₃−CHO, CH₃−COOH

Arrange the following compounds in increasing order of reactivity towards S_N2 reaction.

2-Bromopentane, 1-Bromopentane, 2-Bromo-2-methylbutane

Complete the reaction with the main product formed:

Convert bromoethane to propanamine.

Give the mechanism of the following reaction:

\[\ce{CH3CH2OH ->[H2SO4][413 K] CH3CH2-O-CH2CH3 + H2O}\]