✓ Board-verified
Chemistry · 2023 · 5 marks
The d-and f-Block ElementsGeneral Properties of the Transition Elements (d-Block)5 marksUnderstandlong answer
CBSE 2023 · Region 4 · Set 1 · Q34
(a) (i) Account for the following: (1) Zn^2+ salts are colourless while Ni^2+ salts are coloured. (2) Cr^2+ is a strong reducing agent. (3)…
(i)
Account for the following :
(1)
$\displaystyle \mathrm{Zn}^{2+}$ salts are colourless while $\displaystyle \mathrm{Ni}^{2+}$ salts are coloured.
(2)
$\displaystyle \mathrm{Cr}^{2+}$ is a strong reducing agent.
(3)
Transition metals and their compounds show catalytic activities.
(ii)
Write the ionic equations for the oxidizing action of $\displaystyle \mathrm{MnO}_{4}^{-}$in acidic medium with
(1)
$\displaystyle \mathrm{I}^{-}$ion, and
(2)
$\displaystyle \mathrm{Fe}^{2+}$ ion.
(i)
Name two oxometal anions of the 3d series of the transition metals in which the metal exhibits the oxidation state equal to its group number.
(ii)
What is the effect of increasing pH on a solution of $\displaystyle \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ ?
(iii)
Why is $\displaystyle \mathrm{Cu}^{+}$not stable in aqueous solution ?
(iv)
Name a member of Lanthanoid series which is well-known to exhibit +$\displaystyle 4$ oxidation state.
(v)
Name two elements of 3d series which show anomalous electronic configuration.
Marking-scheme solution
(a) (i)
(1) Because of no unpaired electron in d-orbitals in \(\displaystyle \mathrm{Zn}^{2+}\) whereas, \(\displaystyle \mathrm{Ni}^{2+}\) has $\displaystyle 2$ unpaired electrons in d-orbitals / \(\displaystyle \mathrm{Ni}^{2+}\) shows d-d transition while \(\displaystyle \mathrm{Zn}^{2+}\) does not.
(2) Because Cr is more stable in + $\displaystyle 3$ oxidation state due to stable \(\displaystyle \mathrm{t}_{2 \mathrm{~g}}{ }^{3}\) configuration.
(3) Because of their ability to show multiple or variable oxidation states / ability to form complex / provide larger surface area for the reactants.
(1) \(\displaystyle \mathbf{2 M n O}_{\mathbf{4}}^{-}+10 \mathrm{I}^{-}+16 \mathrm{H}^{+} \longrightarrow 2 \mathrm{Mn}^{2+}+5 \mathrm{I}_{2}+8 \mathrm{H}_{2} \mathrm{O}\)
(2) \(\displaystyle \mathbf{M n O}_{\mathbf{4}}^{-} \boldsymbol{+} \mathbf{5 ~ F e}^{\mathbf{2}+} \boldsymbol{+} \mathbf{8 ~ H}^{+} \longrightarrow \mathbf{M n}^{\mathbf{2}+}+\mathbf{5 ~ F e}^{\mathbf{3}+}+\mathbf{4 ~ H}_{\mathbf{2}} \mathbf{O}\)
All The d-and f-Block Elements questions2023 question paperNCERT solutions: The d-and f-Block ElementsPractice The d-and f-Block Elements →
More from The d-and f-Block Elements
- Assertion: Transition metals show their highest oxidation state with oxygen. Reason (R): The ability of oxygen to form multiple bonds to metals.2023 · asked 2×
- Which of the following transition metals shows +1 and +2 oxidation states?2026 · asked 2×
- Assertion: Actinoids show wide range of oxidation states. Reason (R): Actinoids are radioactive in nature.2025 · asked 2×
- With increase in atomic number, the melting point of transition metals:2025
- In which of the following does the central atom exhibit an oxidation state of+3?2023
- (i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. (ii)…2022
- Give reasons for the following statements: Copper does not displace hydrogen from acids. Transition metals and most of their compounds show…2022
- Which one among the following metals of 3d series has the lowest melting point?2023
CBSE Class 12 Chemistry past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.