Question

examine the nuclear reaction: (ce{_1^1h + _0^1n -> _1^2h}). why is this classified as a nuclear reaction rather than a chemical reaction? (\bigcirc) it is not balanced. (\bigcirc) a new compound is formed. (\bigcirc) a change has occurred in a nucleus. (\bigcirc) a new element has been formed.

Explanation:

1. Analyze the first option: The given nuclear reaction \(\ce{^1_1H + ^1_0n \to ^2_1H}\) is balanced (sum of mass numbers on left: \(1 + 1=2\), on right: \(2\); sum of atomic numbers on left: \(1+ 0 = 1\), on right: \(1\)), so this option is incorrect.
2. Analyze the second option: In this reaction, we are combining a proton (in hydrogen - 1) and a neutron, not forming a new compound. Chemical reactions involve the rearrangement of atoms to form new compounds, while this is a nuclear process. So this option is incorrect.
3. Analyze the third option: Nuclear reactions involve changes in the nucleus (protons or neutrons are added, removed, or transformed). In this reaction, a neutron is added to the nucleus of hydrogen - 1 (\(\ce{^1_1H}\)) to form deuterium (\(\ce{^2_1H}\)), so a change has occurred in the nucleus. This is the key characteristic of a nuclear reaction.
4. Analyze the fourth option: The element on the left is hydrogen (\(Z = 1\)) and the element on the right is also hydrogen (\(Z=1\)), so no new element is formed. So this option is incorrect.

Answer:

C. A change has occurred in a nucleus.