The elements of the "Noble" gases group is nonreactive. The reason for this is that noble gases are always or most of the time at room temperature.<span />
Option (a) is correct.
A reducing agent is the one which loses electrons to other substance.
Here, Zn has oxidation number 0 in the L.H.S of the equation, but on R.H.S its oxidation number is +2 i.e. it Zn has donated two of its electrons to

.
Hence, Zn is the reducing agent here.
Increasing the temperature of the system, will cause the equilibrium to shift toward the direction of the reaction that absorbs heat.
The theoretical yield is 160 g H₂O.
<em>Moles of H₂</em> = 18 g H₂ × (1 mol H₂/2.016 g H₂) = 8.93 mol H₂
<em>Moles of H₂O</em> = 8.93 mol H₂O × (2 mol H₂O/2 mol H₂) = 8.93 mol H₂O
<em>Theoretical yield</em> of H₂O = 8.93 mol H₂O × (18.02 g H₂O/1 mol H₂) = 160 g H₂O