Which decay decreases the atomic number by 1 and emits a positron?

Which decay decreases the atomic number by 1 and emits a positron?

• A. Alpha
• B. Beta Minus
• C. Beta Plus
• D. Gamma

Answer: (A)

Emitting a positron is beta-plus decay. In this process, a proton in the nucleus converts into a neutron, so the atomic number decreases by 1 while the mass number stays the same. A positron is emitted along with a neutrino. The nucleus ends up with one fewer proton but the same total number of nucleons. This differs from alpha decay, which ejects a helium nucleus and reduces both Z and A by larger amounts; and from beta-minus decay, where a neutron becomes a proton and an electron is emitted, increasing the atomic number by 1; gamma decay releases energy as a photon with no change to Z or A.

Emitting a positron is beta-plus decay. In this process, a proton in the nucleus converts into a neutron, so the atomic number decreases by 1 while the mass number stays the same. A positron is emitted along with a neutrino. The nucleus ends up with one fewer proton but the same total number of nucleons.

This differs from alpha decay, which ejects a helium nucleus and reduces both Z and A by larger amounts; and from beta-minus decay, where a neutron becomes a proton and an electron is emitted, increasing the atomic number by 1; gamma decay releases energy as a photon with no change to Z or A.