Question

Which of the following statement is correct:

• A. $H^{+}$ is the smallest size cation in the periodic table
• B. van der Waals radius of chlorine is more than covalent radius
• C. Ionic mobility of hydrated $L{i}^{+}$ is greater than that of hydrated $N{a}^{+}$
• D. $He$ atom has the highest ionisation enthalpy in the periodic table

Answer 1

Answer: (A), (B), (D)

The correct options are
A $H^{+}$ is the smallest size cation in the periodic table
B van der Waals radius of chlorine is more than covalent radius
D $He$ atom has the highest ionisation enthalpy in the periodic table

(a) $H^{+}$ is the smallest cation in the periodic table as it contains $0$ electron.

(b) van der Waals radius of chlorine is more than that of covalent radius because van der Waals radius basically do not consider the overlaps whereas covalent radius is measured when atoms overlap to form bonds.

(c) Ionic mobilities of hydrated alkali metal ions are as:
$C{s}^{+}>R{b}^{+}>K^{+}>N{a}^{+}>L{i}^{+}$
Since hydration is more for smaller cations.

(d) According to the general trend, ionization energy decreases down the group and increases along the period. As can be seen from the position of the $He$ atom in the periodic table, $He$ atom has the highest ionisation enthalpy in the periodic table. $He$ also has a very stable electronic configuration.