At ground level, how are rain and hail similar? They are forms of water in its liquid state.
They occur when the temperature is below freezing.
They can occur when the air is hot and moist.
They are most common in the winter.

Answer : The chemical species X, Y, and Z in the mechanism are , and respectively.

Explanation :

The given overall balanced reaction is:

The two intermediate reactions are:

(1)

(2)

In reaction 1, there are 2 hydrogen atoms present on left side of reaction but there is no hydrogen atom present on right side of the reaction and there are 2 oxygen atoms present on left side of reaction but there is 1 oxygen atom present on right side of the reaction.

So, in order to balance the chemical reaction we are adding water molecule on right side of the reaction. So, the reaction 1 will be:

Thus, the chemical specie X will be

Now comparing the reaction 1 and the overall reaction we conclude that there are 2 molecules of present on right side of the reaction.

So, in order to balance the number of water molecules we are taking the chemical specie Z as and to complete the reaction one molecule are adding on the left side of the reaction 2. So, the reaction 2 will be:

Thus, the chemical specie Z and Y will be and respectively.