The compound that is both paramagnetic and coloured is

• K₂Cr₂O₇

• (NH₄)₂ [TiCl₆]

• V₀SO₄

• K₃[Cu(CN)₄]

Transition elements exhibit variable valencies, because they release electrons from the following orbits

• ns

• ns and np

• (n - 1) d and ns

• nd and (n - 1)d

Although zirconium belongs to 4d and hafnium belongs to 5d transition series even they show similar physical and chemical properties because both

• belong to d- block

• have same number of electrons

• belongs to the same group of the periodic table

• have similar atomic radius

404.

Which of the following good reducing agent?

• Yb²⁺

• Ce⁴⁺

• Tb⁴⁺

• La³⁺

Which of the following will not give tests for free transition metal ion in solution ?

• K₂[Ni(CN)₄]

• FeSO₄.K₂SO₄.24H₂O

• Both of the above

• None of the above

Zinc oxide loses oxygen on heating according to the reaction

$\mathrm{ZnO} \stackrel{\mathrm{Heat}}{\to } {\mathrm{Zn}}^{2+} + \frac{1}{2}{\mathrm{O}}_2 + 2{\mathrm{e}}^{-}$

It becomes yellow on heating because

• Zn²⁺ ions and electrons move too interstitial sites and F-centres are created.

• Oxygen and electron moves at the crystal and ions become yellow

• Zn²⁺ again combine with oxygen to give yellow oxide

• Zn²⁺ are replaced by oxygen.

Which of the following does not exist?

• KI + I₂ → KI₃

• KF + F₂ → KF₃

• KBr + ICI₂ → K[BrICl]

• KF + BrF₃ → K[BrF₄]

Which of the following does not represent the correct order of the property indicated?

• Sc³⁺ > Cr³⁺ > Fe³⁺ >Mn³⁺ - ionic radii

• Sc < Ti < Cr < Mn - density

• Mn²⁺ >Ni²⁺ > Co²⁺ <Fe²⁺ - ionic radii

• FeO < CaO < MnO < CuO - basic nature

Which of the following oxidation states is the most common among the lanthanoids?

• 4

• 2

• 3

• 5

Mn₂O₇ dissolves in water to give an acid. The colour of the acid is

• green

• blue

• purple

• red