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.
What is the basic theme of organisation in the periodic table?
Before the 18th century, only a 31 elements are known & it was quite east to study their chemical & physical properties. But with the passage of time, more & more elements were discovered. By 1865, the number of identified element had more than doubled to 63. At present 114 elements are known. It was not possible to study & remember each of them individually . Because many of them have different properties.So, there arise the need of developing a table in which all the elements can be classified according to similar properties so that less confusion can be generated & true information can be generated by the different elements present in the periodic table.
What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?
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 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?
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