Name any two noble gases.

Find the number of electrons,protons,and neutrons possessed by the alpha particles $\left({ }_{2}^{4} He ^{2+}\right)$ used in the gold leaf experiment.

State whether the following statement is true or false:
Atomic radius is measured in nanometres. $1 \, m = 10^9 \, nm$.

List three differences between electron, proton, and neutron.

Give one point of similarity and one point of difference between isotopes of ${ }_{6}^{14} C$ and ${ }_{6}^{12} C$.

Write the names of three elementary particles which constitute an atom. Which of these particles determine the mass of an atom? Justify your answer with an example.