When $PbO_2$ reacts with concentrated $HNO_3$,the evolved gas is:

Which oxide of nitrogen is a coloured gas?

$\underbrace{2NO + O_2}_{(X)} \rightleftharpoons \underbrace{2NO_2}_{(Y)} \underset{heat}{\overset{cold}{\longleftrightarrow}} \underbrace{N_2O_4}_{(Z)}$
$X, Y$ and $Z$ can be described as:

$P_{4}O_{10}$ reacts with water to produce

Which one of the following is not a colourless compound?

Select the correct statement.