State whether the following statement is true or false:
An atom of each element has a definite combining capacity,called its valency.

Rutherford designed an experiment to determine the structure of an atom. Answer the following in relation to this experiment:
$(a)$ Name the element he selected for this purpose.
$(b)$ Which subatomic particle was used by him?
$(c)$ What was the drawback of Rutherford's model of the atom?

$(a)$ Why are anode rays called canal rays?
$(b)$ Mention two postulates of $J. J.$ Thomson's model.
$(c)$ Compare the properties of protons and electrons.

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.

The first model of an atom was given by

An ion $X^{2-}$ contains $10$ electrons and $8$ neutrons. What are the atomic number and mass number of element $X$?