The atomic numbers of four elements P, Q, R and S are 6, 8, 14 and 16 respectively. Out of these, the element known as metalloid is

In Mendeleev’s periodic table, gaps were left for the elements to be discovered later on. An element which found a vacant place in the periodic table later on is :

The three imaginary elements X, Y and Z represent a Dobernenner’s triad. If the atomic mass of element X is 14 and that of element Y is 46, then the atomic mass of element Z will be :

Which of the following statement is correct in regard to the classification of elements ?

Which of the following statement about the modern periodic table is correct?