A science museum's touring exhibition includes a large mechanical model of an atom for visitors to explore. A small plaque fixed to one of the modelled particles reads: relative charge = 0, relative mass = 1 Which particle does this plaque describe?

Answer: B. Step 1: Recall the relative charge and relative mass of each particle Particle Relative charge Relative mass proton +1 1 neutron 0 1 electron -1 1/1840 (negligible) Step 2: Match the plaque's data to a particle The plaque states a relative…

IGCSE Chemistry 0620: Relative Charge and Mass of Subatomic Particles

Step 1: Recall the relative charge and relative mass of each particle

Particle	Relative charge	Relative mass
proton	$+1$	$1$
neutron	$0$	$1$
electron	$-1$	$\tfrac{1}{1840}$ (negligible)

Step 2: Match the plaque’s data to a particle

The plaque states a relative charge of $0$ and a relative mass of $1$ .

The proton has charge $+1$ , so it does not match.
The electron has a negligible mass, so it does not match.
The neutron has charge $0$ and relative mass $1$ , this matches exactly.
The nucleus is not a single particle at all; it is the structure made up of protons and neutrons together, so it cannot be described by a single charge and mass pair in this way.

Why the other options are wrong

A (proton): correct relative mass ( $1$ ), but wrong charge ( $+1$ , not $0$ ).
C (electron): correct charge ( $-1$ , not $0$ , so actually wrong on both counts), and its mass is negligible, not $1$ .
D (nucleus): describes a whole cluster of particles, not one particle with a single charge and mass.

Final answer

The plaque describes a $\boxed{\text{neutron}}$ , option B.