Which has the smallest size

$\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OH} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{C{H_3}{\text{ }} - {\text{ }}CH{\text{ }} = {\text{ }}CH{\text{ }} - {\text{ }}C{H_3}\xrightarrow{{{H_3}{O^ + }}}\,C{H_3} - C{H_2} - CH - C{H_3}}
\end{array}$

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The enthalpy change $(\Delta H)$ for the reaction $N_2(g) + 3H_2(g) \to 2NH_3(g)$ is $-92.38\, kJ$ at $298\, K$. The internal energy change $\Delta U$ at $298\, K$ is......$kJ$

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The molecular formulae for phosgene and tear gas are $.......... $ and $......... $ respectively.

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Of the following, the largest value of entropy at $25^{\circ} C$ and $1\, atm$ is that of

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The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is :

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A gas expands from $3\,dm^3$ to $5.8\, dm^3$ against constant external pressure of $3$ $bar$. The work done during expansion is used to heat $2$ moles of water from $290\,K$ to final temperature of $T\,K$. If specific heat of water is $4.2\, J-gm^{-1} \,K^{-1}$, then $T=......K$

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$(A)$ will be