A pair of metals which dissolves in sodium hydroxide solution is

(1) Cu, K    

(2) Fe, Mg

(3) Ag, Cu               

(4) Sn, Zn

When ${\mathrm{I}}^{-}$ is oxidised by ${\mathrm{MnO}}_4^{-}$ in alkaline medium, ${\mathrm{I}}^{-}$ converts into-

1. ${\mathrm{IO}}_3^{-}$

2. ${\mathrm{I}}_2$

3. ${\mathrm{IO}}_4^{-}$

4. ${\mathrm{IO}}^{-}$

Which one of the following statements related to lanthanum is incorrect?

1.  Europium shows +2 oxidation state.

2.  The basicity decreases as the ionic radius decreases from pr to Lu.

3.  All the lanthanoids are much more reactive than aluminum.

4.  Ce⁺⁴ solution are widely used as the oxidizing agents in volumetric analysis.

The reason for greater range of oxidation states in actinoids is attributed to:

1. Actinoid Contraction.

2. 5f, 6d and 7s levels having comparable energies.

3. 4f and 5d levels being close in energies.

4. The radioactive nature of actinoids

Which one of the following statements is correct when SO₂ is passed through acidified K₂Cr₂O₇solution?

1. The solution is decolorized.

2. SO₂ is reduced.

3. Green coloured Cr₂(SO₄)₃ is formed.

4. The solution turns blue.

Gadolinium belongs to 4f series. It’s atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

1. $\left[Xe\right]4 f^8 6d^2$

2. $\left[Xe\right]4 f^9 5s^1$

3. $\left[Xe\right]4 f^7 5d^{1}6s^2$

4. $\left[Xe\right]4 f^6 5d^{2}6s^2$

Assuming complete ionization, same moles of which of the following compounds will require the the least amount of acidified KMnO₄ for complex oxidation?

1. $FeS{O}_4$

2. $FeS{O}_3$

3. $Fe{C}_2{O}_4$

4. $Fe{\left(N{O}_2\right)}_2$

Magnetic moment 2.84 BM is given by (At. no. Ni = 28, Ti = 22, Cr = 24, Co = 27)

$1. {\mathrm{Ni}}^{2+}$
$2. {\mathrm{Ti}}^{3+}$
$3. {\mathrm{Cr}}^{3+}$
$4. {\mathrm{Co}}^{2+}$