Which of the following elements can combine with chlorine to form more than one binary compound?

1. Zn

2. K

3. Ca

4. Fe

\(FeCr_{2}O_{4} \) when reacts with $N{a}_{2}C{O}_3$ gives the product: 

1. $N{a}_{2}Cr{O}_4$

2. $N{a}_{2}C{r}_2{O}_7$

3. $F{e}_3{O}_4$

4. FeO

A set of ions among the following that have a 3d² electronic configuration is:

1. ${\mathrm{Ti}}^{+},{\mathrm{V}}^{4+},{\mathrm{Cr}}^{6+},{\mathrm{Mn}}^{7+}$

2. ${\mathrm{Ti}}^{4+},{\mathrm{V}}^{3+},{\mathrm{Cr}}^{2+},{\mathrm{Mn}}^{3+}$

3. ${\mathrm{Ti}}^{2+},{\mathrm{V}}^{3+},{\mathrm{Cr}}^{4+},{\mathrm{Mn}}^{5+}$

4. ${\mathrm{Ti}}^{3+},{\mathrm{V}}^{2+},{\mathrm{Cr}}^{3+},{\mathrm{Mn}}^{4+}$

The general electronic configuration of lanthanoids is:

1. (n – 2) f ^1–14 (n – 1) s² p⁶ d^0–1 ns²

2. (n – 2) f ^10–14 (n – 1) d^0–1 ns²

3. (n – 2) f ^0–14 (n – 1) d¹⁰ ns²

4. (n – 2) d^0–1 (n – 1) f ^1–14 ns²

Zn gives H₂ gas with H₂SO₄ and HCl but not with HNO₃ because:
 

An incorrect statement among the following is :

The catalytic activity of transition metals is due to:

The basic character of the transition metal monoxides follows the order:
(Atomic nos. Ti = 22, V = 23, Cr = 24, Fe = 26)

The correct order of ionic radii of Y³⁺, La³⁺, Eu³⁺, and Lu³⁺ is:

(Atomic nos. Y = 39, La = 57, Eu = 63, Lu = 71)

1. Y³⁺ < La³⁺ < Eu³⁺ < Lu³⁺

2. Y³⁺ < Lu³⁺ < Eu³⁺ < La³⁺

3. Lu³⁺ < Eu³⁺ < La³⁺ < Y³⁺

4. La³⁺ < Eu³⁺ < Lu³⁺ < Y³⁺

Mn²⁺ compounds are more stable than Fe²⁺ compounds towards oxidation in their +3 state because :