What's the problem ? Hardness is not the definition of a metal.
You need to expand your thinking. EVERY element is solid, liquid, and gas, over different ranges of temperature ... including all of the metals. There are only TWO elements that are liquid AT ROOM TEMPERATURE, and mercury is one of them. But on a mild day at the south pole, mercury is solid too.
Explanation:
The relation between
is given by :

Where :
= Ionic prodcut of water
The value of the first ionization constant of sodium sulfite = 
The value of
:


The value of the second ionization constant of sodium sulfite = 
The value of
:


I think the answer would be nitrogen
The first option is the correct.
Since we know the mass of one atom of Fe is 56 and that of Cl2 atoms is 71 (one atom has 35.5 mass) hence both of them will be consumed