Which of the following chemicals contains chlorine?

State whether the following statements are True or False:
$(1)$ The metal and non-metal elements of $d$-block react with hydrogen to give molecular hydrides.
$(2)$ At normal temperature,dihydrogen reacts violently with dioxygen.

Very pure hydrogen $(99.9\%)$ can be made by which of the following processes?

The hydride ions $({H^{-}})$ are isoelectronic with

The product$(s)$ of the reaction $NaBH_4 + I_2 \longrightarrow$ 'Products' is/are

The name hydrogen was given by