Which of the following two ions have the same number of unpaired electrons ?

(1) Mn³⁺       (2) Fe³⁺      (3) Cr³⁺      (4) Co³⁺

• (2) and (3)

• (3) and (4)

• (1) and (2)

• (1) and (4)

The lanthanoid contraction is responsible for the fact that

• Zn and Y have about same radius

• Zr and Nb have similar oxidation states

• Zr and Hf have about the same radius

• Zr and Zn have the same oxidation state

The equivalent weight of MnSO₄, is equal to its molecular weight when it is converted to

• Mn₂O₃

• MnO₂

• MnO${}_4^{-}$

• MnO${}_4^{2-}$

The mineral from which potassium permanganate is manufactured

• manganite, Mn₂O₃.H₂O

• pyrolusite, MnO₂

• Both (a) and (b)

• None of the above

Which one of the following transition metal ion is coloured?

• Cu⁺

• Zn²⁺

• Sc³⁺

• V⁴⁺

Correct order of paramagnetism is

• Mn>Cr> Zn

• Fe> Zn> Cr

• Cr> Fe> Zn

• Zn >Mn> Fe

The aqueous ferrous ion is green, ferric ion is pale yellow. The aqueous chromic ion is green, hence the colour of chromate ion must be

• orange

• colourless

• yellow

• red

138.

In acidic medium, the equivalent weight of  K₂Cr₂O₇ (Mol. wt. = M) is

• M

• M/2

• M/3

• M/6

${}_{92}{}^{235}\mathrm{U}$ belongs to IIIB group of the Periodic.When it loses one α -particle, the new element will belong to the group.

• I B

• V B

• I A

• III B

Which set of elements have nearly the same atomic radii ?

• F, Cl, Br, I

• Na, K, Rb, Cs

• Fe, Co, Ni, Cu

• Li, Be, B, C