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The D-And-f-Block Elements

Question
CBSEENCH12011131
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KMnO4 can be prepared from K2MnO4 as per reaction
3 MnO subscript 4 superscript 2 minus end superscript space plus 2 straight H subscript 2 straight O space rightwards harpoon over leftwards harpoon 2 MnO subscript 4 superscript minus space plus MnO subscript 2 space plus 4 OH to the power of minus
The reaction can go to completion by removing OH- ions by adding

  • HCl

  • KOH

  • CO2

  • SO2

Solution

D.

SO2

Since OH- are generated from weak acid (H2O), a weak acid (like CO2) should be used to remove it because of a strong acid (HCl) reverse the reaction, KOH increases the concentration of OH-, thus again shifts the reaction in the backwards side. 
CO2 combines with OH- to give carbonate which is easily removed. 
SO2 reacts with water to give strong acid, so it cannot be used. 

Some More Questions From The d-And-f-Block Elements Chapter

In the series Sc (Z = 21) to Zn(Z = 30), the enthalpy of atomisation of zinc is the lowest i.e., 26, kJ mol. Why?

The E° (M2+/M) value for copper is positive (+ 0.34 V). What is possibility the reason for this? 

How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?

Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

Which is a stronger reducing agent Cr2+ or Fe2+ and why?

Explain why Cu+ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d10 4s1, yet it is considered transition element. Why?

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