\((1)\) Weight of \(H _{2}=\) mole \(\times\) molecular weight

\(=0.2 \times 2\)

\(=0.4\, g\)

\((2)\) \(6.023 \times 10^{23}= 1 \,mol\)

\(6.023 \times 10^{22}= 0.1 \,mol\)

The weight of Nitrogen,

\(N _{2}=0.1 \times 28=2.8 \,g\)

\((3)\) Weight of silver is \(0.1 \,g\)

\((4)\) Weight of oxygen \(=32 \times 0.1=3.2\, g\)