The following diagram depicts the Rutherford’s experiment.

Why was zinc sulphide screen is used in the experiment?

Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order.

(i) Rutherford's atomic model

(ii) Thomson's atomic model

(iii) Bohr's atomic model.

Which of the following are true for an element?

(i )Atomic number $=$ Number of protons $+$ number of electrons

(ii) Mass number $=$ Number of protons$+$ number of neutrons

(iii) Atomic mass $=$ Number of protons$=$ Number of neutrons

(iv) Atomic number $=$ Number of protons$=$ Number of electrons.

Different isotopes are matched with their uses as

(i) $\mathrm{Co}-60$-To treat cancer

(ii) $\mathrm{U}-238$-To produce electricity

(iii) $\mathrm{I}-131$-To treat goitre

(iv) $\mathrm{Na}-24$-In agricultural research

Which of the above matches are correct?