CBSE 2023 · Region 2 · Set 3 · Q26 · 3 marks
Answer any $\displaystyle 3$ of the following: $\displaystyle \mathbf{3} \boldsymbol{\times} \mathbf{1}$(a)Which isomer of $\displaystyle \mathrm{C}_{5} \mathrm{H}_{10}$ gives a single monochloro compound $\displaystyle \mathrm{C}_{5} \mathrm{H}_{9} \mathrm{C} l$ in bright sunlight?(b)Arrange the following compounds in increasing order of reactivity towards $\displaystyle \mathrm{S}_{\mathrm{N}} 2$ reaction: $\displaystyle 2$-Bromopentane, $\displaystyle 1$-Bromopentane, $\displaystyle 2$-Bromo-$\displaystyle 2$-methylbutane(c)Why p-dichlorobenzene has higher melting point than those of ortho- and meta-isomers?(d)Identify A and B in the following:
Answer any $\displaystyle 3$ of the following: $\displaystyle \mathbf{3} \boldsymbol{\times} \mathbf{1}$
(a)
Which isomer of $\displaystyle \mathrm{C}_{5} \mathrm{H}_{10}$ gives a single monochloro compound $\displaystyle \mathrm{C}_{5} \mathrm{H}_{9} \mathrm{C} l$ in bright sunlight?
(b)
Arrange the following compounds in increasing order of reactivity towards $\displaystyle \mathrm{S}_{\mathrm{N}} 2$ reaction: $\displaystyle 2$-Bromopentane, $\displaystyle 1$-Bromopentane, $\displaystyle 2$-Bromo-$\displaystyle 2$-methylbutane
(c)
Why p-dichlorobenzene has higher melting point than those of ortho- and meta-isomers?
(d)
Identify A and B in the following:
Marking-scheme solution
(a) Cyclopentane
(b) $\displaystyle 2$-Bromo-$\displaystyle 2$-methylbutane < $\displaystyle 2$-Bromopentane < $\displaystyle 1$-Bromopentane
(c) Because para isomer fits well into the crystal lattice due to symmetry.
(d) 
Haloalkanes and HaloarenesChemical Reactions of Haloalkanes and HaloarenesUnderstandshort_answermedium
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CBSE Class 12 Chemistry past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.