Which of the following would produce a buffer solution when mixed in equal volumes?

Hydrolysis of $NCl_3$ gives $NH_3$ and $X$. Which of the following is $X$?

Which of the following reagents reacts with benzaldehyde to produce $1$-phenylethanol?

The $RNA$ can be removed by treatment with ............. whereas proteins can be removed by treatment with .............. in the isolation of $DNA$ from a cell.

Wires $A$ and $B$ have resistivities $\rho_A$ and $\rho_B$,where $\rho_B = 2 \rho_A$,and have lengths $l_A$ and $l_B$. If the diameter of wire $B$ is twice that of $A$ and the two wires have the same resistance,then the ratio $\frac{l_B}{l_A}$ is:

Two rectangular blocks,having identical dimensions,can be arranged either in configuration $I$ or in configuration $II$ as shown in the figure. One of the blocks has thermal conductivity $k$ and the other $2k$. The temperature difference between the ends along the $x-$ axis is the same in both the configurations. It takes $9 \ s$ to transport a certain amount of heat from the hot end to the cold end in the configuration $I$. The time to transport the same amount of heat in the configuration $II$ is .......... $\sec$.