The density of $400 \text{ cm}^3$ of palm oil was $0.9 \text{ g}\cdot\text{cm}^{-3}$ before frying. If the density of the oil was $0.6 \text{ gcm}^{-3}$ after frying, assuming no loss of oil due to spilling, its new volume was?

Natural radioactivity consists of the emission of

Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

If the fraction of the atoms of a radioactive material left after $120$ years is $\frac{1}{64}$, what is the half-life of the material?