During which radioactive decay process does a neutron change into a proton? A. Alpha decay
B. Gamma decay
C. Beta decay (positron)
D. Beta decay (electron)

QUESTIONS:- During which radioactive decay process does a neutron change into a proton?

A. Alpha decay

B. Gamma decay

C. Beta decay (positron)

D. Beta decay (electron)

ANSWER:-

D. Beta decay (electron)

Beta decay occurs when, in a nucleus with too many protons or too many neutrons, one of the protons or neutrons is transformed into the other.

In beta minus (β−) decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.