Which of the following reactions give $\mathrm{H}_2$ as one of the products?

(Reactions are not balanced)

I. $\mathrm{NaBH}_4+\mathrm{I}_2 \longrightarrow$

II. $\mathrm{B}_2 \mathrm{H}_6+\mathrm{N}\left(\mathrm{CH}_3\right)_3 \rightarrow$

III. $\mathrm{Al}+\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \longrightarrow$

IV. $\mathrm{BF}_3+\mathrm{NaH} \longrightarrow$

Consider the following.

Statement $\mathrm{IH}_2 \mathrm{O}_2$ acts as an oxidising as well as reducing agent in both acidic and basic mediim.

Statement $\mathrm{II} 10 \mathrm{~V} \mathrm{H}_2 \mathrm{O}_2$ sample means it contains $6 \% \left(\frac{w}{v}\right) \mathrm{H}_2 \mathrm{O}_2$.

The correct answer is

Which of the following property is less for $\mathrm{D}_2 \mathrm{O}$ than $\mathrm{H}_2 \mathrm{O}$ ?