COMEDK2024Evening ShiftChemistryd and f Block ElementsActual
Identify the correct statement from the following.
Options
- ACr ( VI ) is more stable than W ( VI ) and hence acts as a good oxidising agent
- BInterstitial compounds of transition metals have lower melting points than that of pure transition metals and
- CCerium is a lanthanoid metal which exists in a stable oxidation state of +4 , besides exhibiting an oxidation
- DThe green manganate ion shows diamagnetic nature but the permanganate ion exhibits paramagnetic nature
Correct answer
C. Cerium is a lanthanoid metal which exists in a stable oxidation state of +4 , besides exhibiting an oxidation
Step-by-step solution
Correct answer: (3) (1) Incorrect: Higher oxidation states become more stable down the group, so W(VI) is more stable than Cr(VI). Cr(VI) is less stable and hence acts as a strong oxidising agent. (2) Incorrect: Interstitial compounds have higher melting points than pure metals (lattice becomes more rigid), and they are chemically inert. (3) Correct: Cerium (Ce) is a lanthanoid showing +3 state normally, but also exists in a stable +4 state since Ce⁴⁺ achieves noble gas configuration [Xe]4f^0 . (4) Incorrect: MnO₄²