Use the equation to answer the question.

Question

21H+ 21H→ 42H+energy


Which statement best describes the mass numbers of the atoms in the reaction?

(1 point)
Responses

There is one atom with a mass number of 2.
There is one atom with a mass number of 2.

There is one atom with a mass number of 1.
There is one atom with a mass number of 1.

There are two atoms with mass numbers of 2.
There are two atoms with mass numbers of 2.

There are two atoms with mass numbers of 1.

Answer 1

The reaction given is:

\( 21H + 21H \rightarrow 42H + \text{energy} \)

In this reaction, \( 21H \) represents deuterium, which is an isotope of hydrogen with a mass number of 2 (1 proton, 1 neutron). The product \( 42H \) represents helium (more specifically, a helium nucleus) with a mass number of 4.

To analyze the mass numbers:

• The reactants consist of two \( 21H \) atoms, each with a mass number of 2. Therefore, there are two atoms with mass number 2.
• The resulting product is \( 42H \), which has a mass number of 4.

Given this analysis, the correct statement is:

"There are two atoms with mass numbers of 2."