Download App

The d & f Block Elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements5 Marks
Question

Answer the following questions:

  1. The figure given alongside illustrates the first ionization enthalpies of first, second and third series of transition elements. Answer the question that follows:
  2. Which series amongst the first, second and third series of transition elements have the highest first ionization enthalpy and why?
  3. Separation of lanthanoid elements is difficult. Explain.
  4. Sm2+, Eu2+ and Yb2+ ions in solutions are good reducing agents but an aqueous solution of Ce4+ is a good oxidising agent. Why?

✓

Answer

  1. Third series has the highest first ionization energy due to poorest shielding effect of the fully filled 4fsubshell.
  2. This is due to lanthanoid contraction.
  3. Sm2+, Eu2+ and Yb2+ ions are good reducing agents as they tend to acquire common oxidation state of +3 shown by lanthanoids by the loss of one electron while Ce4+ gains one electron to attain +3. Hence, Ce4+ is an oxidising agent.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from The d & f Block Elements→The d & f Block Elements — all question types→Chemistry STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Explain the collision principle of any chemical reaction.
→
Prove that boiling point elevation (AT) is proportional to the molality of solute present in the solution. Also find its mathematical form.
→
(a) Draw the structure of a galvanic cell and also describe the reaction taking place in it.
(b) What happens when opposite external potential is applied in the galvanic cell system? Explain.
→
Explain the methods of preparation alcohol from the following compounds:
(a) From carbonyl compound
(b) From carboxylic acid
(c) From esters
(d) From Grignard reagent
→
  1. Account for the following:
  1. Transition metals form large number of complex compounds.
  2. The lowest oxide of transition metal is basic whereas the highest oxide is amphoteric or acidic.
  3. E° value for the Mn3+/Mn2+ couple is highly positive (+1.57 V) as compare to Cr3+/Cr2+. 56/1/1 9.
  1. Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
→
Explain different types of isomerism in amines.
→
An aromatic compound ‘A’ on treatment with CHCl3/ KOH gives two compounds ‘B’ and ‘C’. Both B and C give the same product ‘D’ when distilled with zinc dust. Oxidation of D gives E having molecular formula C7H6O2. The sodium salt of E on heating with sodalime gives F which may also be obtained by distilling A with zinc dust. Identify A to F.
→
  1. Complete the following chemical equations for reactions:

i. $\text{MnO}_{4(aq)}^{-}+\text{S}_{2}\text{O}_{3(aq)}^{2-}+\text{H}_{2}\text{O}_{(l)}\rightarrow$

ii. $\text{Cr}_{2}\text{O}^{-}_{7(aq)}+\text{H}_{2}\text{S}_{(g)}+\text{H}^{+}_{(aq)}\rightarrow$

  1. Give an explanation for each of the following, observations:
  1. The gradual decrease in size (actinoid contraction) from element to element is greater among the .actinoids than that among the lanthanoids (lanthanoid contraction).
  2. The greatest number of oxidation states are exhibited by the members in the middle of a transition series.
  3. With the same d-orbital configuration (d4) Cr2+ ion is a reducing agent but Mn3+ ion is an oxidising agent.

 

→
(a) What is van't Hoff factor? Explain.
(b) Write the equation of molecular number properties including van't Hoff factor.
→
  1. Answer the following questions briefly:
  1. What are any two good sources of vitamin A?
  2. What are nucleotides?
  3. Give an example of simple lipids.
  1. How are carbohydrates classified?
→