Question

Hen an electric current passes through liquid water, hydrogen gas passes accumulates at one electrode and oxygen accumulates at the other. Which of the following is true?
A) A physical change has occurred, with energy is being absorbed.

B) A chemical change has occurred, with energy being given off.

C) A physical change has occurred, with energy being given off.

D) A chemical change has occurred, with energy being absorbed.

Answer 1

The correct option is D.
The reaction above is called dissociation of water, that is, water is broken down into oxygen and hydrogen through the passage of electric current. This is an example of a chemical reaction. The reaction is an endothermic reaction because energy is absorbed.

Answer 2

Answer:The correct answer is option D.

Explanation:

Physical change : It is defined as change in shape, state or size of the substance. There is no change in composition of the substance and no new substance is formed.

Chemical change : it is defined as change in chemical composition of the substance. During this change formation of new substance takes place.

Decomposition of water can be written as:

$H_2O(l)\overset{Electricity}\rightarrow H_2(g)+O_2(g)$

In above decomposition reaction, energy is provided to the water molecule to break down into its constituent elements that is oxygen and hydrogen. Energy given to the molecule is in the form electrical energy.

Hence, yes it is a chemical change.