Question

if water is made of hydrogen and oxygen then why we cannot take oxygen by drinking water​

Answer 1

Answer: because water contain less

Amount of oxygen in it . That's why we can not breath in water

Explanation:

Answer 2

Answer:

for separating oxygen and hydrogen it requires 2000 degree centigrade temperature which i think may not possible in human body........

and also

In the case of hydrogen and oxygen gas, if you react them together one way you get liquid water (H2O). The reason we cannot breathe liquid water is because the oxygen used to make the water is bound to two hydrogen atoms, and we cannot breathe the resulting liquid. The oxygen is useless to our lungs in this form.