After finding the oxidation states of atoms, you identify the half reactions (option c).
The half reactions are given by the change of the oxidation states of the atoms.
For example if Cu is in the left side with oxidation state 0 and in the other side with oxidation state 2+, then there you have a half reaction (oxidation reaction). And if you have O with oxidation state 0 in the left side and with oxidation state 2- in the right side, there you have other half reaction (reducing reaction).
You’ll need to be sure to count all the atoms in each side of the chemical equation.
Answer : The new volume of the air is, 6.83 L
Explanation :
Charles' Law : It states that volume of the gas is directly proportional to the temperature of the gas at constant pressure.
Mathematically,

where,
are the initial volume and temperature of the gas.
are the final volume and temperature of the gas.
We are given:

Putting values in above equation, we get:

Therefore, the new volume of the air is, 6.83 L
Explanation:
The number of nitrogen atoms in one mole of nitrogen gas are <em><u>6.02214179×1023 nitrogen </u></em><em><u>atoms</u></em><em><u>.</u></em><em><u> </u></em>
<em>Hope this helps... </em>
A, B, C, and D, because they are changing from a solid to a liquid, liquid to solid, and solid to gas. Phase changes are when a solid, liquid, or gas, turns into a solid, liquid, or gas. Ex. Ice melting is a solid changing into a liquid. Hope this helps!