ICSE Class 10 Answered

Dear Student,

(a) Carbon, Fluorine, Beryllium (decreasing order of atomic size) -  Atomic size decreases from left to right across the period.

Hence, the decreasing order of atomic size would be:

Berylium (Grp 2, period 2)  > Carbon (Grp. 4, period 14)  > Fluorine (Grp. 17, period 2)

(b) Sulphuric acid, Phosphoric acid, Acetic acid (increasing order of number of replaceable H atoms per molecule)

Sulphuric acid (H₂SO₄) - 2

Phosphoric acid (H₃PO₄) - 3

Acetic Acid (CH₃COOH) - 1

(c) Potassium, Lithium, Sodium (increasing order of ionization potential)

Ionisation potential decreases down the group.

Hence, the increasing order of ionisation potential would be:

Potassium ( grp 1, period 4) < Sodium (grp 1, period 3) < Lithium (grp 1, period 2)