Question

Which of these is an example of a chemical change?

Answer 1

Answer: Forming oxygen By bubbling flourine through water

Explanation:

Chemical change is the change in which chemical composition of the substance changes by rearrangement of atoms.

Physical change is a change in which only the physical properties such as size, shape etc change and there is no rearrangement of atoms.

1. Dissolving two cups of flour in a liter changes the state and hence is a physical change.

2. Pouring water from a large trough into a beaker is a physical change.

3. Decreasing the motion of water molecules by freezing changes the state and hence is a physical change.

4. Forming oxygen By bubbling flourine through water involve rearrangement of atoms and thus is a chemical change.

$F_2+H_2O\rightarrow 2HF+O_2$

Answer 2

Forming oxygen by bubbling fluorine through water.