Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

How is the variability in oxidation states of transition metals different from that of p-block elements?

The oxidation state of Fe in [Fe(CO)₅] is ______.

Which of the following characteristics of transition metals is associated with their catalytic activity?

Do the following conversions in not more than two steps:

\[\begin{array}{cc}
\ce{CH3CN to CH3 - C - CH3}\\
\phantom{...........}||\\
\phantom{...........}\ce{O}
\end{array}\]

Do the following conversions in not more than two steps:

Account for the following:

Sc³⁺ is colourless whereas Ti³⁺ is coloured in an aqueous solution.

Account for the following:

Ce⁴⁺ is a strong oxidising agent.

Assertion (A): Transition metals have high enthalpy of atomisation.

Reason (R): Greater number of unpaired electrons in transition metals results in weak metallic bonding.

Which one among the following metals of the 3d series has the lowest melting point?

Which of the following transition metals shows +1 and +2 oxidation states?

Assertion (A): Transition metals show their highest oxidation state with oxygen.

Reason (R): The ability of oxygen to form multiple bonds to metals.

Which property of transition metals enables them to behave as catalysts?

Why is the C-O bond length in phenols less than that in methanol?

Complete the following reaction and justify that it is a disproportionation reaction:

\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]

The given graph shows the trends in melting points of transition metals:

Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.

Consider the following standard electrode potential values:

\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\], E⁰ = +0.77 V

\[\ce{MnO^{-4}_{ (aq)} + 8H^+ + 5e^- -> Mn^{2+}_{ (aq)} + 4H2O_{(l)}}\], E⁰ = +1.51 V

What is the cell potential for the redox reaction?

Which of the following ions has the electronic configuration 3d⁶?
(Atomic number: Mn = 25, Co = 27, Ni = 28)

A transition element X has an electronic configuration [Ar]4s²3d³. Predict its likely oxidation states.

Consider the following standard electrode potential values:

\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E⁰ = −0.14 V

\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E⁰ = +0.77 V

What is the cell reaction and potential for the spontaneous reaction that occurs?

Write the number of unpaired electrons in Cr³⁺.
(Atomic number of Cr = 24)