The properties of Zr and Hf are same because :

• they have similar radii

• they belong to d-block

• they have same valence electrons

• None of the above

Formation of coloured solution is possible when metal ion in the compound contains :

• paired electrons

• lone pair of electrons

• unpaired electrons

• None of the above

283.

In the periodic table metals usually used as catalysts belong to :

• f - block

• d - block

• p - block

• s - block

In a neutron induced reaction of ${}_{92}{}^{235}\mathrm{U}$ , the product obtained is ${}_{37}{}^{95}\mathrm{Rb}$ , three neutrons and an element (new nuclide) .The other new nuclide is :

• ${}_{55}{}^{138}\mathrm{Cs}$

• ${}_{56}{}^{140}\mathrm{Ba}$

• ${}_{54}{}^{144}\mathrm{Xe}$

• ${}_{38}{}^{90}\mathrm{Sr}$

The electronic configuration of Cr³⁺ is :

• [Ar] 3d⁴ 4s²

• [Ar] 3d³ 4s⁰

• [Ar] 3d² 4s¹

• [Ar] 3d⁵ 4s¹

The lanthanide contraction is responsible for the fact that :

• Zr and Zn have the same oxidation state

• Zr arid Hf have about the same radius

• Zr and Nb have similar oxidation state

• Zr and Y have about the same radius

Which of the following forms a colourless solution in aqueous medium ?

• Cr³⁺

• V³⁺

• Sc³⁺

• Ti³⁺

The atomic number of Ni and Cu are 28 and 29 respectively .The electronic configuration 1s , 2s² 2p⁶ , 3s² 3p⁶ 3d¹⁰ represents :

• Cu⁺

• Cu²⁺

• Ni²⁺

• Ni

Assertion : Transition metals are poor reducing agents.

Reason : Transition metals form numerous alloys
with other metals.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : The degree of complex formation in actinides decreases in the order ${\mathrm{M}}^{4+} > {\mathrm{MO}}_2^{2+} > {\mathrm{M}}^{3+} > {\mathrm{MO}}_2^{+}$.

Reason : Actinides form complexes with p-bonding ligands such as alkyl phosphines and thioethers.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.