$A$ soft heavy metal melts at $30\ ^oC$ and is used in making heat-sensitive thermometers. The metal is:

Which compound is related to Haber's process?

Which oxide of nitrogen is a coloured gas?

Which of the following metals does not exhibit the inert pair effect?

Which blue liquid is obtained on reacting equimolar amounts of two gases at $-30\,^oC$?

Cyclic polymetaphosphates have the general formula of $[P_nO_{3n}]^{n-}$. Cyclic trimeric polymetaphosphate $(P_3O_9)^{3-}$ has commercial importance. Which of the following is not true regarding $P_3O_9^{3-}$?