Hypophosphorous acid is

The important method for the fixation of nitrogen is

Which of the following statements regarding $N_2O_4$ is not correct?

The molecular formula of an acid of phosphorus is $H_3PO_2$. What are its name and basicity,respectively?

$A$ $p$-block element $(E)$ and hydrogen form a binary cation $(EH_{x}^{+})$, while $EH_{3}$ on treatment with $K_{2}HgI_{4}$ in alkaline medium gives a precipitate of basic mercury$(II)$amido-iodine. Given below are first ionisation enthalpy values $(kJ \ mol^{-1})$ for the first element of each group $13, 14, 15$, and $16$. Identify the correct first ionisation enthalpy value for element $E$.

What is the number of hydroxyl groups in pyrophosphoric acid?