From the symbol $^4_2\text{He}$ for the element helium, write down the mass number and the atomic number of the element.

Sulphur has an atomic number of 16 and a mass number of 32. State the number of protons and neutrons present in the nucleus of sulphur.

$^{24}${12}\text{Mg} and $^{26}{12}\text{Mg}$ are symbols of two isotopes of magnesium. Compare the atoms of these isotopes with respect to :

(i) the composition of their nuclei.

(ii) their electronic configurations.

(iii) give the reason why the two isotopes of magnesium have different mass numbers.

Chlorine is an element of atomic number 17. It is a mixture of two isotopes having mass number of 35 and 37.

(i) What is meant by 'atomic number of an element' ? What do you understand by an 'atom'.

(ii) Write down the electronic configuration of the chlorine atom.

(iii) State the number of protons, electrons and neutrons in the following isotopes: $^{35}\text{Cl}${17}, $^{37}\text{Cl}{17}$

(iv) Explain why the two atoms in (iii) above have the same chemical reactions.

(v) If molten magnesium chloride is electrolyzed suggest a suitable electrode [anode].