The electronic configuration of Palladium is:

1. [Kr] 5f³ 6d¹ 7s²

2. [Kr] 5f⁵ 6d¹ 7s²

3. [Kr] 5f² 6d¹ 7s²

4. None of the above.

The formation of the oxide ion, O²⁻(g), from an oxygen atom occurs in two successive steps:

O(g) + e⁻ → O⁻(g)  ΔH = −141 kJ mol⁻¹

O⁻(g) + e⁻ → O²⁻(g)  ΔH = +780 kJ mol⁻¹

Although O²⁻ is isoelectronic with neon, its formation in the gaseous state is energetically unfavourable. What is the main reason for this?

Identify the correct order of the size of the following:

1. $C{a}^{2+}<K^{+}<Ar<S^{2-}<C{l}^{-}$

2. $C{a}^{2+}<K^{+}<Ar<C{l}^{-}<S^{2-}$

3. $Ar<C{a}^{2+}<K^{+}<C{l}^{-}<S^{2-}$

4. $C{a}^{2+}<A{r}^{+}<K^{+}<C{l}^{-}<S^{2-}$

For the second-period elements, the correct increasing order of first ionisation enthalpy is:

The incorrect order of electronegativity is :

The element having electronic configuration [Kr]4d¹⁰4f¹⁴, 5s²5p⁶, 6s² belongs to:

1. s-block

2. p-block

3. d-block

4. f-block

The electronegativity of the following elements increases in the order:

1. C, N, Si, P

2. N, Si, C, P

3. Si, P, C, N

4. P, Si, N, C

The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on electrons in its outer shell is :

1. s > p > d > f

2. f > d > p > s

3. p < d < f < s

4. f > p > s > d

Which of the following groups of elements is characterized by the progressive filling of 4f orbitals?