The catalyst used in the contact process is

Which of the following is a polyamide?

Which of the following national parks is not a habitat for tigers?

In Gattermann reaction,a diazonium group is replaced by $\underline{X}$ using $\underline{Y}$. $\underline{X}$ and $\underline{Y}$ are:
$\underline{X} \quad \underline{Y}$

If $A = \{2, 4, 5\}$ and $B = \{7, 8, 9\}$,then $n(A \times B)$ is equal to:

At $90 \, ^\circ C$,the concentration of $[H_3O^+]$ in pure water is $10^{-6} \, M$. What is the value of $K_w$ at this temperature?