Lanthanoids are:
 

1.	14 elements in the seventh period (atomic no. = 90 to 103) that are filling 5f sublevel.
2.	14 elements in the sixth period (atomic no. 58 to 71) that are filling 4f sublevel
3.	14 elements in the seventh period (atomic no. = 58 to 71) that are filling 4f sublevel
4.	14 elements in the sixth period (atomic no. 90 to 103) that are filling 4f sublevel

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

An element among the following that shows the maximum number of oxidation states is:

1. Cr

2. Fe

3. Mn

4. V

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)