A cloud chamber contains supersaturated alcohol vapour, which condenses on ions produced in the air to form visible tracks.

An experiment uses a radioactive source that emits both $\alpha$-particles and $\beta$-particles. In the cloud chamber:

• some tracks (Type A) are short, thick, and straight.
• other tracks (Type B) are longer, thinner, and less straight.

State and explain which tracks are produced by $\alpha$-particles and which are produced by $\beta$-particles.

$\alpha$-particles: $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$

$\beta$-particles: $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$

A radioactive isotope of phosphorus ($P$) is used as a tracer to study how plants absorb nutrients from soil. A nucleus of this isotope of phosphorus contains 15 protons and 17 neutrons. This nucleus decays by emitting a $\beta$-particle to form a nucleus of sulfur ($S$).

Describe what is meant by an isotope. $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$

Write down the nuclide equation for the decay of this isotope of phosphorus to sulfur.

This isotope of phosphorus has a half-life of $14days$. The isotope of sulfur produced is stable and does not undergo radioactive decay.

Suggest why these properties of the phosphorus isotope and the sulfur isotope make this phosphorus isotope suitable for use as an agricultural tracer. $\dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots \dots$