Give an account of properties of caustic soda (NaOH)?

1) NaOH react with Al metal to form sodium meta Alluminate.
$2\mathrm{Al}+2\mathrm{NaOH}+2{\mathrm{H}}_2\mathrm{O}\to 2{\mathrm{NaAlO}}_2+3{\mathrm{H}}_2$
2) Cold, dilute NaOH react with Cl₂ to forms NaCl and NaOCl
$2\mathrm{NaOH}+{\mathrm{Cl}}_2\to \mathrm{NaCl}+\underset{(\mathrm{sodium} \mathrm{hypochlorite})}{\mathrm{NaOCl}}+{\mathrm{H}}_2\mathrm{O}$
3) Hot con. NaOH react with Cl₂ to form NaCl and NaClO₃.
$6\mathrm{NaOH}+3{\mathrm{Cl}}_2\to 5\mathrm{NaCl}+\underset{(\mathrm{sodium} \mathrm{chlorate})}{{\mathrm{NaClO}}_3}+3{\mathrm{H}}_2\mathrm{O}$
4) NaOH react with white phosphorus to form phosphine.
$3\mathrm{NaOH}+{\mathrm{P}}_4+3{\mathrm{H}}_2\mathrm{O}\to 3{\mathrm{NaH}}_2{\mathrm{PO}}_2+{\mathrm{PH}}_3$
5) NaOH react with sulphur to form sodium thiosulphate.
$6\mathrm{NaOH}+4\mathrm{S}\to {\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3+2{\mathrm{Na}}_2\mathrm{S}+3{\mathrm{H}}_2\mathrm{O}$
6) NaOH react with SiO₂ to form water glass 
$2\mathrm{NaOH}+{\mathrm{SiO}}_2\to \underset{(\mathrm{water} \mathrm{glass})}{{\mathrm{Na}}_2{\mathrm{SiO}}_3}+{\mathrm{H}}_2\mathrm{O}$