d- and f-Block Elements Chapter-Wise Test 1

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following statements about lanthanoids is INCORRECT?

Lanthanoids primarily exhibit +3 oxidation state. Only a few elements like Eu and Yb show +2 oxidation state. Therefore, the statement that they primarily exhibit +2 oxidation state is incorrect.

They are silvery-white soft metals
They primarily exhibit +2 oxidation state
They show lanthanoid contraction
They form colored ions
2

Which of the following represents the preparation of KMnO4 from pyrolusite ore?

In the first step, MnO2 is oxidized with KOH in the presence of O2 to form K2MnO4:
2MnO2 + 4KOH + O2 → 2K2MnO4 + 2H2O

Reduction of MnO2 with carbon
Oxidation of MnO2 with KOH and O2
Electrolysis of MnSO4
Heating MnO2 with HCl
2

What is the lanthanoid contraction?

Gradual decrease in atomic/ionic radii of lanthanoids due to poor shielding by 4f electrons.

Increase in atomic size across the series
Decrease in density of lanthanoids
Decrease in atomic/ionic radii across the series
Increase in metallic character
3

Which of the following is NOT a consequence of lanthanoid contraction?

Lanthanoid contraction leads to similar atomic sizes of Zr and Hf, but it does not affect ionization energy trends.

Similar atomic radii of Zr and Hf
Difficult separation of lanthanoids
Increase in density across the series
Decrease in ionization energy
4

What happens when K2Cr2O7 is treated with an alkali?

Dichromate (Cr2O72−) converts to chromate (CrO42−) in alkaline medium: Cr2O72− + 2OH− → 2CrO42− + H2O. The solution turns yellow due to chromate formation.

Forms CrO42− (yellow)
Forms Cr3+ (green)
No reaction
Forms MnO4−
1

Which of the following reactions represents the preparation of K2Cr2O7 from chromite ore?

Chromite ore is oxidized with Na2CO3 in the presence of air to form sodium chromate:
4FeCr2O4 + 8Na2CO3 + 7O2 → 8Na2CrO4 + 2Fe2O3 + 8CO2. This is the key step in the preparation of K2Cr2O7.

Oxidation of chromite with Na2CO3 in air
Reduction of chromite with carbon
Electrolysis of chromite
Heating chromite with HCl
1

Which catalyst is used in the hydrogenation of vegetable oils?

Finely divided nickel (Ni) is used as a catalyst in hydrogenation reactions.

V2O5
Ni
Fe
Pt
2

Which of the following is NOT true about lanthanoid contraction?

Lanthanoid contraction causes decrease in size, not increase, due to poor shielding by 4f electrons.

Causes similar atomic sizes of Zr and Hf
Results from poor shielding by 4f electrons
Increases atomic radii across the series
Affects properties of post-lanthanoid elements
3

Which actinoid is most commonly used in nuclear reactors?

Uranium (U) is the primary fuel in nuclear reactors due to its fissionable isotopes.

Thorium (Th)
Uranium (U)
Plutonium (Pu)
Neptunium (Np)
2

Which of the following statements about actinoids is correct?

Actinoids exhibit variable oxidation states due to comparable energies of 5f, 6d, and 7s orbitals, allowing participation of multiple electrons in bonding.

They show only +3 oxidation state
They are non-radioactive
They exhibit variable oxidation states
They do not form complexes
3

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