The incorrect statement among the following is: 

1.	Zirconium and Hofnium have identical radii of 160 pm and 159 pm, respectively, as a consequence of lanthanoid contraction.
2.	Lanthanoids reveal only a +3 oxidation state.
3.	Lanthanoid ions, other than the f0 type and the f14 type, are all paramagnetic.
4.	The overall decrease in atomic and ionic radii from lanthanum to lutetium is called lanthanoid contraction.

An example of the effect of the concentration of nitric acid on the formation of oxidation products would be:

1. 3Cu + 8HNO₃   →   3Cu(NO₃)₂   +   2NO   +   4H₂O

2. Cu   +   4HNO₃   →   3Cu(NO₃)₂   +   2NO₂   +   2H₂O

3. Both (1), and (2)

4. None of the above

Match the following characteristics to the appropriate metal:  

Select the correct option :

Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵: Atomic number for the element X is :

1. 25

2. 26

3. 27

4. 24

An ements among the following that has the highest density is -

(1) Fe 

(2) Ni

(3) Co

(4) Cu

Which compound exhibits colour in its solid state?

1. Ag₂SO₄

2. CuF₂

3. ZnF₂

4. Cu₂Cl₂

Among the following, which are amphoteric oxides?

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

The correct value of the spin-only magnetic moment of $C{r}^{3+}$ ion is equal to:

Which of the following statements is false?  

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 :