QCAA Physics Alternative Sequence Ionising radiation and nuclear reactions

Correct. This is Einstein's famous mass-energy equivalence formula, stating that energy ($E$) equals mass ($m$) times the speed of light squared ($c^2$).

Incorrect. This is the formula for gravitational potential energy, where $g$ is the acceleration due to gravity and $h$ is height.

Incorrect. This incorrectly combines the structure of the kinetic energy formula with the speed of light ($c$), which does not represent any standard physical relationship.

Incorrect. This is the classical formula for kinetic energy, representing the energy of an object in motion with mass $m$ and velocity $v$.

This is correct because each half-life reduces the mass by half. Starting with $16\text{ g}$, it takes 4 half-lives to reach $1\text{ g}$ ($16 \rightarrow 8 \rightarrow 4 \rightarrow 2 \rightarrow 1$).

This is incorrect. After 5 half-lives, the remaining mass would be halved one more time, leaving only $0.5\text{ g}$ of sodium-24.

This is incorrect. After 6 half-lives, the remaining mass would be $16 \times (1/2)^6 = 0.25\text{ g}$, not $1\text{ g}$.

This is incorrect. After 8 half-lives, the remaining mass would be $16 \times (1/2)^8 = 0.0625\text{ g}$.