Predict the formulae of the stable binary compounds that would be formed by the following pairs of elements:
calcium and iodine

Predict the formula of the stable binary compounds which would be formed by the following pairs of elements:

(i) element 114 and fluorine

(ii) element 120 and oxygen.

Discuss briefly the anomalous behviour of elements of second period.
Or
The first element of each group differs significantly from rest of the elements of the same group. Give reasons.

What do you understand by diagonal relationship?

Show by a chemical reaction with water that Na₂O is a basic oxide and Cl₂O₇ is an acidic oxide. 

What is the basic theme of organisation in the periodic table?

What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

Explain why cation are smaller and anions larger in radii than their parent atoms?

Among the second period elements the actual ionisation enthalpies are in the order 
Li<B<Be<C<O<N<F<Ne.
Explain why
(i) Be has higher  than B
(ii) O has lower  than N and F?