Question

select the answer from the menu.
when an atom gains an electron, the atom will
lose a proton
reduce its mass
become radioactive
have a negative charge

Explanation:

To solve this, we analyze each option:

• "lose a proton": Gaining an electron doesn't cause proton loss. Protons are in the nucleus, and electron gain is a charge - related change, not a proton change.
• "reduce its mass": Electrons have mass (albeit small). Gaining an electron would increase mass slightly, not reduce it.
• "become radioactive": Radioactivity is related to nuclear changes (like proton/neutron changes), not electron gain.
• "have a negative charge": Atoms are neutral (protons = electrons). Gaining an electron means electrons > protons, so the atom (now an ion) has a negative charge.

Answer:

have a negative charge