Group A elements are called

Both elements of 1st period contain valence electrons in

A. M shell

B. N shell

C. K shell

D. S shell

In the periodic table, helium is placed at

A. top left corner

B. bottom right corner

C. bottom left corner

D. top right corner

Across the period the atomic size decreases due to

A. shielding effect

B. photoelectric effect

C. increase in nuclear force of attraction

D. decrease in nuclear force of attraction

The first three periods are

A. long periods

B. short periods

C. moderate periods

D. all of above

On basis of electronic configuration the group and period of ⁹₅B is

A. 2 and IIIA

B. 3 and IIA

C. 4 and VIA

D. 5 and VIIA