Metallic radii of some transition elements are given below. Which of these elements will have highest density?

Element	Fe	Co	Ni	Cu
Metallic radii/pm	126	125	125	128

    

1.	Fe	2.	Ni
3.	Co	4.	Cu

The coloured compound among the following in the solid state is:
1. \( \mathrm{Ag}_{2} \mathrm{SO}_{4} \)
2. \(\mathrm {C u F}_{2} \)
3. \(\mathrm {Zn F}_{2} \)
4. \(\mathrm{Cu}_{2} \mathrm{Cl}_{2} \)

On addition to a small amount of KMnO₄ to concentrated H₂SO₄, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following.

1. Mn₂O₇

2. MnO₂

3. MnSO₄

4. Mn₂O₃

The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of the transition element, which shows the highest magnetic moment.

Which of the following oxidation state is common for all lanthanoids?

Which of the following reactions are disproportionation reactions?

\(\left(\right. i \left.\right)   C u^{+}     \rightarrow     C u^{2 +}   +   C u\)
\(\left(\right. i i \left.\right)   3 M n O_{4}^{-}   +   4 H^{+}         \rightarrow           2 M n O_{4}^{-}   +   M n O_{2}   +   2 H_{2} O\)
\(\left(\right. i i i \left.\right)   2 K M n O_{4}           \rightarrow           K_{2} M n O_{4}   +   M n O_{2}   +   O_{2}\)
\(\left(\right. i v \left.\right)   2 M n O_{4}^{-}   +   3 M n^{2 +}   +   2 H_{2} O         \rightarrow           5 M n O_{2}   +   4 H^{+}\)

1.  (i)

2.  (i) , (ii) and (iii)

3.  (ii) , (iii) and (iv)

4.  (i) and (iv)

When $KMn{O}_4$ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because

1.  $C{O}_2$ is formed as the product

2.  Reaction is exothermic

3.  $Mn{O}_4^{-}$ catalyses the reaction

4.  $M{n}^{2+}$ acts as autocatalyst

There are 14 elements in the actinoid series. Which of the following elements does not belong to this series?

$KMn{O}_4$ acts as an oxidizing agent in an acidic medium. The number of moles of $KMn{O}_4$ that will be needed to react with one mole of sulphide ions in an acidic solution is$\mathrm{:}$

Which of the following is amphoteric oxide ?