Important Questions Class 12 Chemistry Chapter 8 The d and f Block Elements 1 Mark Questions

1. Zinc, cadmium and mercury are not considered as transition metals. Why?

Ans. Zinc, cadmium and mercury have fully filled configuration. Therefore they are not considered as transition metal.

2. Write the general configuration of d- block elements.

Ans. General electronic configuration of d- block elements is.

3. What are the factors that decide the ionization potential?

Ans.The ionization potential values are governed by various ionization enthalpy values, bond enthalpy values and hydration enthalpy values.

4. What are interstitial compounds. Give two examples

Ans. Compounds formed by trapping small atoms like H, C, or N inside the crystal lattices of metals eg. TiC,  etc.

5. What is the ore of  ?

Ans. Potassium dichromate  chromite ore  Potassium Permanganatepyrolusite.

6. What is the effect of adding a base to potassium dichromate?

Ans. When a base is added to orange coloured potassium dichromate its colour changes to yellow due to formation of potassium chromate.

7. Draw the structure of chromate and dichromate ions?


8. Draw the structure of manganate and permanganate ions?


9. Complete and balance:-













10. Name the two series of f-block.

Ans.The two series are-

i) 4f series or Lanthanoids         ii)        5f series or actinoids.

11. The chemistry of actionoids is more complicated than lanthanoids. Why?

Ans.The complications in the actinoid series is due to

i)Existence of a wide range of oxidation states.        ii)     Their radioactivity.

12.What is the general valance configuration of f-block elements?

Ans. The general electronic configuration of f-block elements is 

13. What is the most common oxidation state of lanthanoids and actionoids?

Ans. The common oxidation states of

(1)  4f series is +3

(2) 5f series is +3, +4, +5, +6 & +7

14. Actionoid contraction is more than lanthanoid contraction. Give reason.

Ans.The actinoid contraction is more than Lanthanoid contraction as the shielding

Power of 5f orbitals is poorer than 4f orbitals.

15. What is the composition of mischmetall? Give its one use.

Ans. Mischmetall is an alloy of a Lanthanoid metal and iron and traces of S, C, Ca &

Al. It is used in Magnesium based alloy to produce bullets, shell and lighter Flint.

16. Actionoids show larger number of oxidation states than lanthanoids. Why?

Ans. Actinoids can show many oxidation states as in actinoids 5f orbitals are filled which are not as buried as Lanthnoids and can also participate in bonding to a greater extent besides 6d and 7s electrons.

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Class 12 Chemistry MCQ Questions for Term 1 Exam

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