Question

When electricity is passed through water:
(a)- Hydrogen is evolved at anode
(b)- Oxygen gas is evolved at cathode
(c)- Hydrogen is evolved at cathode
(d)- No changes occur

Answer 1

In water, there are two parts, i.e., positive part and negative part. When electricity is passed by dipping the electrodes, then the positive part will be a cathode and the negative part will be at the anode.

Complete answer:
We know that when electricity is produced there is the involvement of the positive part and the negative part. Therefore, in the conduction of electricity, there is the involvement of two types of electrodes, i.e., cathode and anode. The charge on the cathode is positive and the charge on the anode is negative.
These electrodes are dipped in a substance that is capable of splitting into ions which will conduct electricity. When electricity is passed by dipping the electrodes, then the positive part will be a cathode and the negative part will be at the anode.
So, the given compound in the question is water. As we know that water contains two elements, i.e., hydrogen and oxygen, and oxygen is negative while hydrogen is positive. So, when the electricity is passed then the hydrogen is evolved at cathode while the oxygen gas is evolved at anode.

Therefore, the correct answer is an option (c)- Hydrogen is evolved at cathode.

Note:
In a galvanic cell, in which chemical reactions lead to the generation of electrical energy the charge on the electrodes can be reversed as a charge on the cathode can be positive and the charge on the anode can be negative.