Comprehension given below is followed by some multiple choice questions. Each question has one correct option.

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In the modern periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four block, viz., s, p, d and f.
The modern periodic table consists of 7 periods and 18 groups each period begins with the filling of a new energy shell In accordance with the Aufbau principle, the seven periods (1 to 7) have 2, 8, 8, 18, 18, 32 and 32 elements respectively. The seventh period is still incomplete to avoid the periodic table being too long, the two series of /-block elements, called lanthanoids and actinoids are placed at the bottom of the main body of the periodic table