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

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.

Do the following conversions in not more than two steps:

CH₃COOH to CH₃COCH₃

Do the following conversions in not more than two steps:

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)

Which of the following statements is not true about glucose?

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)

Account for the following:

Copper has an exceptionally positive `"E"_("M"^(2+)//"M")^0` value.

Account for the following:

Eu²⁺ with electronic configuration [Xe]4f⁷6s² is a strong reducing agent.

The trend of which property is represented by the following graph?

Radioactive decay follows first-order kinetics. The initial amount of two radioactive elements X and Y is 1 gm each. What will be the ratio of X and Y after two days if their half-lives are 12 hours and 16 hours respectively?

In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe and Zn are -0.25 V, -0.44 V and -0.76 V respectively.)

The second ionization enthalpies of chromium and manganese are 1592 and 1509 kJ/mol respectively. Explain the lower value of Mn.