When hydrogen atoms combine to form molecules of hydrogen, 433 KJ/mol energy is released.



Whenever atoms combine to form a molecule ,there is always decrease in the energy. Actually, when two H atoms are far separated, they do not have any force of interaction (attractive or repulsive). As they tend to come closer, two different forces operates:

(a) The nucleus of one H is attracted towards the electrons of the other H atoms & Vice versa. The energy is released in attraction.

(b) The nuclei of the atoms as well as their electrons repel each other. Energy is needed to overcome the force of repulsion.

Now in case, if the magnitude of the attractive forces is more than that of the repulsive forces, a stable molecule will be formed.

However, if the repulsive forces are more than the attractive forces , then the atoms will not combine.

Kharif crops need lot of rainfall whereas wheat need winter season and not rainfall so if wheat is sown in kharif season the crop will be damaged due to rain and there will be collection of water in the fields