Question

Which of the following statement about hydrogen is incorrect ?

• A. Hydrogen never acts as cation in ionic salts
• B. Hydronium ion, $\ce{H_3O^+}$ exists freely in solution
• C. Dihydrogen does not act as a reducing agent
• D. Hydrogen has three isotopes of which tritium is the most common

Answer 1

The Correct Option is D

Hydrogen as a Hydride 

Hydrogen exists as a hydride \({(H^{-})}\) in ionic salts.

The most abundant form of hydrogen is **protium**.

Dihydrogen (\({H_2}\)) can reduce some metal ions in aqueous solutions and oxides of metals (less active than iron) into their corresponding metals.

For example:

\({H_2(g) + Pd^{2+}(aq) \rightarrow Pd(s) + 2H^{+}(aq)}\)

Additionally, dihydrogen can react with metal oxides:

\({yH_2(g) + M_x O_y(s) \rightarrow xM(s) + yH_2O(\ell)}\)