Short Answer TypePredict 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.
Long Answer TypeDiscuss 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.
Short Answer TypeShow by a chemical reaction with water that Na2O is a basic oxide and Cl2O7 is an acidic oxide.Â
What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?
Mendeleev periodic law states that the physical & chemical properties of the elements are a periodic function of their atomic masses. In his periodic table, the elements are arranged in vertical rows called groups & horizontal rows are known as periods.There are nine groups & seven periods. He arranged only 60 elements in periodic table.
 An English physicist Moseley, in 1913 gave modern periodic law which states that the physical & chemical properties of the elements are the periodic function of their atomic number.This law becomes the base of modern periodic law.In the modern periodic table, there are 18 groups & 7 periods.
Long Answer TypeOn the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Short Answer TypeLong Answer TypeAmong the second period elements the actual ionisation enthalpies are in the orderÂ
Li<B<Be<C<O<N<F<Ne.
Explain why
(i) Be has higher 
 than B
(ii) O has lower 
 than N and F?
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