Only terminal alkynes react with ammoniacal silver nitrate to give white precipitate of silver acetylides.

When 1, 3 - dimethylcyclopentene is heated with ozone and then with zinc and acetic acid, oxidative cleavage leads to keto - aldehyde.

Compound $$X$$  reacts with ammonical $$AgN{O_3}$$  solution, so it must be a terminal alkyne. Formation of $${\left( {C{H_3}} \right)_2}CHCOOH$$    on oxidation of $$X$$  with hot alkaline $$KMn{O_4}$$  further confirms that $$X$$  is $${\left( {C{H_3}} \right)_2}CHC \equiv CH.$$

TIPS/Formulae :
Hydration of alkynes via mercuration takes place in accordance with Markovnikov's manner rule
\[C{H_3}C{H_2}C = CH\xrightarrow[{HgS{O_4}/{H_2}S{O_4}}]{{ + 2{H_2}O}}\]       \[\left[ C{{H}_{3}}C{{H}_{2}}\underset{\begin{smallmatrix} | \\ \,\,\,OH \end{smallmatrix}}{\overset{\begin{smallmatrix} \,\,\,\,OH \\ | \end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{3}} \right]\xrightarrow{-{{H}_{2}}O}\]       \[C{{H}_{3}}C{{H}_{2}}\underset{\begin{smallmatrix} \parallel \\ O \end{smallmatrix}}{\mathop{-C-}}\,C{{H}_{3}}\]

Boiling point of alkanes increases with increase in molecular mass and for the same alkane the boiling point decreases with branching.
Thus, the decreasing order of their boiling points is :
$$\mathop {n{\text{ - Pentane }}}\limits_{\left( {{\text{iii}}} \right)} {\text{ > }}\mathop {{\text{2 - Methylbutane}}}\limits_{\left( {{\text{ii}}} \right)} {\text{ }}$$      $${\text{ > }}\mathop {{\text{2, 2 - Dimethylpropane }}}\limits_{\left( {{\text{iv}}} \right)} $$    $${\text{ > }}\mathop {n{\text{ - Butane }}}\limits_{\left( {\text{i}} \right)} $$

The reaction follows Markownikoff rule

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