2. A chemical reaction occurs when substances interact and their atoms O A. disappear
B. change their size.
C. become new atoms.
O D. rearrange

Chemical reactions occur when chemical bonds between atoms are formed or broken. The substances that go into a chemical reaction are called the reactants, and the substances produced at the end of the reaction are known as the products.

Explanation:

The approximate molar mass of NaOH is 40 g/mol. You have 4 g NaOH.

No. of moles of NaOH is given by

n=(Given mass)/(Molar mass)

= 4/40 = 0.1 mol

1 mol has 6.022 × 10^23 molecules.

Thus, 0.1 mol has 6.022 × 10^23 × 0.1 molecules i.e. 6.022 × 10^22 molecules.

Explanation: