Question

When a radioactive magnesium (Mg) atom decays by emitting a positron, what is the identity of the resulting atom? A. Aluminum (Al) B. Magnesium (Mg) C. Neon (Ne) D. Sodium (Na)

Answer 1

The answer is: D. Sodium (Na).

Beta decay is radioactive decay in which a beta ray and a neutrino are emitted from an atomic nucleus.

There are two types of beta decay: beta minus and beta plus.

In beta plus decay (atomic number Z is decreased by one), a proton is converted to a neutron and positron and an electron neutrino, so mass number does not change.

In this example, magnesium (atomic number 12) is converted to dosium (atomic number 11).