Which of the following reagents can form a hydrazone with alkanone?

Viruses are ..........

Which of the following complexes exhibits both geometrical and optical isomerism?

Which of the following is a polyamide?

If $x$ is real, then the minimum value of $\frac{x^2-x+1}{x^2+x+1}$ is

The molar heat of formation of $NH_4NO_{3(s)}$ is $-367.54 \ kJ$ and those of $N_2O_{(g)}$ and $H_2O_{(l)}$ are $+81.46 \ kJ$ and $-285.78 \ kJ$ respectively at $25 \ ^oC$ and $1.0 \ atm$ pressure. Calculate $\Delta U$ at $25 \ ^oC$ for the reaction:
$NH_4NO_{3(s)} \to N_2O_{(g)} + 2H_2O_{(l)}$ (in $kJ$)