$1)\,2/34\,g\,NaCl\times \frac{1mol\,NaCl}{58/5g\,NaCl}=0/04\,mol\,NaCl$ $2)\,1/38\,g\,Na\,\times \frac{1\,mol\,Na}{23\,g\,Na}=0/06\,mol\,Na$ $3)\,0/56\,L{{H}_{2}}\times \frac{1mol\,{{H}_{2}}}{22/4L\,{{H}_{2}}}=0/025\,mol\,{{H}_{2}}$ $4)\,2LC{{L}_{2}}\times \frac{2/84\,g\,C{{l}_{2}}}{1\,L\,C{{l}_{2}}}\times \frac{1\,mol\,C{{l}_{2}}}{71\,g\,C{{l}_{2}}}=0/08\,mol\,C{{l}_{2}}$