Which has more number of atoms, $50\mathrm{g}$ sodium or $50\mathrm{g}$ of calcium? (Given atomic mass of $\mathrm{Na}=23\mathrm{u},\mathrm{Ca}=40\mathrm{u}$) 

Verify whether the following equations are balanced or not? If not, balance it.

${\mathrm{KClO}}_3\to \mathrm{KCl}+{\mathrm{O}}_2\uparrow$

Verify whether the following equations are balanced or not? If not, balance it.

${\mathrm{CaCO}}_3+\mathrm{HCl}\to {\mathrm{CaCl}}_2+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2\uparrow$

Verify whether the following equations are balanced or not? If not, balance it.

${\mathrm{N}}_2+{\mathrm{H}}_2\to {\mathrm{NH}}_3$