Which of the following biomolecules acts as specific catalysts in biological reaction?

Nitrobenzene on reduction with zinc and \(\mathrm{NH}_4 \mathrm{Cl}\) gives

In which of the following substances will hydrogen bonds be strongest?

Which among the following pair constitute a buffer?

Which of the following is an endothermic
reaction?

Which of the products indicates the presence of sulphur atom in an organic compound, in qualitative elemental analysis?

From the following data
\[
\begin{aligned}
& \mathrm{CH}_3 \mathrm{OH}(l)+\frac{3}{2} \mathrm{O}_2(g) \longrightarrow \mathrm{CO}_2(g)+2 \mathrm{H}_2 \mathrm{O}(l) \\
& \Delta_r H^{\circ}=-726 \mathrm{~kJ} \mathrm{~mol}^{-1} \\
& \mathrm{H}_2(g)+\frac{1}{2} \mathrm{O}_2(g) \longrightarrow \mathrm{H}_2 \mathrm{O}(l) \text {; } \\
& \Delta_r \mathrm{H}^{\circ}=-286 \mathrm{~kJ} \mathrm{~mol}^{-1} \\
& \mathrm{C}(\text { graphite })+\mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g}) \text {; } \\
& \Delta_r \mathrm{H}^{\circ}=-393 \mathrm{~kJ} \mathrm{~mol}^{-1} \\
&
\end{aligned}
\]
The standard enthalpy of formation of \(\mathrm{CH}_3 \mathrm{OH}(l)\) in \(\mathrm{kJ} \mathrm{mol}^{-1}\) is

Assertion (A) Helium has lowest boiling point (4.2 K).
Reason (R) The forces that exist between helium atoms are weak dispersion forces.

Assertion (A): If \(B\) is a \(3 \times 3\) matrix and \(|B|=6\), then \(|\operatorname{Adj}(B)|=36\)
Reason (R): If \(B\) is a square matrix of order \(n\), then \(|\operatorname{Adj}(B)|=|B|^{\mathbf{n}}\)

Which of the following polymer is biodegradable?

Two point sources \(S_1\) and \(S_2\) are \(24 \mathrm{~cm}\) apart. Where should a convex lens of focal length \(9 \mathrm{~cm}\) be placed in between them, so that the images of both sources are formed at the same place?

The system of equations \(3 x+2 y+z=6\), \(3 x+4 y+3 z=14\) and \(6 x+10 y+8 z=a\), has infinite number of solutions, if \(a\) is equal to

An open air pipe of length \(80 \mathrm{~cm}\) has the second harmonic frequency equal to the fundamental frequency of a closed organ air pipe. The length of the closed pipe is