Among the following, which are amphoteric oxides?

1. V₂O₅, Cr₂O₃
2. Mn₂O₇, CrO₃
3. CrO, V₂O₅
4. V₂O₅, V₂O₄

Highest oxidation state of manganese in fluoride is +4 (Mn$F_4$) but the highest oxidation state in oxides is +7 (Mn₂O₇). The reason is :

Based on the metallic radii provided, which transition element exhibits the highest density?

1. Fe 

2. Ti

3. Co

4. Cu

The electronic configuration of gadolinium (atomic number of 64) is:

1. $\left[\mathrm{Xe}\right]4{\mathrm{f}}^{3}5{\mathrm{d}}^{5}6{\mathrm{s}}^2$

2. $\left[\mathrm{Xe}\right]4{\mathrm{f}}^{7}5{\mathrm{d}}^{2}6{\mathrm{s}}^1$

3. $\left[\mathrm{Xe}\right]4{\mathrm{f}}^{7}5{\mathrm{d}}^{1}6{\mathrm{s}}^2$

4. $\left[\mathrm{Xe}\right]4{\mathrm{f}}^{8}5{\mathrm{d}}^{6}6{\mathrm{s}}^2$

Match Column I (Catalyst) with Column II (Process), and mark the appropriate option:

Codes:

Urea reacts with water to form A, which decomposes to form B. When B is passed through ${\mathrm{Cu}}^{2+}$ (aq), a deep blue-colored solution C is formed

The formula of C is: 

1. ${\left[\mathrm{Cu}{\left({\mathrm{NH}}_3\right)}_4\right]}^{2+}$

2. $\mathrm{Cu}{\left(\mathrm{OH}\right)}_2$

3. ${\mathrm{CuCO}}_3.\mathrm{Cu}{\left(\mathrm{OH}\right)}_2$

4. ${\mathrm{CuSO}}_4$

Match the following characteristics to the appropriate metal:  

Select the correct option :

Actinoids show a greater number of oxidation states than lanthanoids because:  

Which of the following is a result of the lanthanide contraction?

1. Zr and Y have nearly the same atomic radius.

2. Zr and Zn have the same oxidation state. 

3. Zr and Hf have nearly the same atomic radius.

4. Zr and Nb have similar oxidation states.

The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate solution will be:

1. +2

2. +3

3. +4

4. +6