Arrange the following in order of increasing radii:
(a) `CI- , CI`
(b) `Mg^(2+), Mg, Mg^+`
(c) `N, O, P`
First ionization enthalpy of two elements X and Y are 500KJ `mol-^1` and 375KJ `mol-^1` respectively. Comment about their relative position in a group as well as in a period.
A metal M forms as oxide having the formula `M_2O_3`. It belongs to third period. Write the atomic number and valency of the metal.
This question refers to the elements of the periodic table with atomic number from 3 to 18. Some of the elements are shown by letters, but the letters are not the usual symbols of the elements.
Which of these:
(a) have most electronegative element.
(b) is a halogen?
(c) is an alkali metal?
(d) is an element with valency 4?
(e) have least ionization energy?
(f) have least atomic size in period 3.