Download App

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

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements5 Marks
Question
  1. Account for the following:
  1. $Mn_2O_7$ is acidic whereas $MnO$ is basic.
  2. Though copper has completely filled d-orbital $(d^{10})$ yet it is considered as a transition metal.
  3. Actinoids show wide range of oxidation states.
  1. Write the preparation of potassium permanganate from pyrolusite ore $(MnO_2).$
✓

Answer

  1.  
  1. Because of higher oxidation state $(+7)$ of $Mn.$
  2. Because it has one unpaired electron in 3d orbital in its $+2$ oxidation state / or it has incompletely filled d-orbital in $+2$ oxidation state.
  3. Because of comparable energies of $5f, 6d$ and $7s$ orbitals.
  1. $2\text{MnO}_2\text{ }+\text{ }4\text{KOH}\text{ }+\text{ }\text{O}_2\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }}2\text{K}_2\text{MnO}_4\text{ }+\text{ }2\text{H}_2\text{O}$
$3\text{MnO}_4\text{ }^{2-}+\text{ }4\text{H}^+\text{ }\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }}2\text{MnO}_4\text{ }^-+\text{MnO}_2+\text{ }2\text{H}_2\text{O}$

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

  1. Answer the following questions briefly:
  1. What are reducing sugars?
  2. What is meant by denaturation of a protein?
  3. How is oxygen replenished in our atmosphere?
  1. Define enzymes.
→
What is crystal field theory? On the basis of this, explain the crystal field splitting in octahedral coordinaton compounds.
→
Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron(II) ions (ii) $SO_2$ and (iii) oxalic acid? Write the ionic equations for the reactions.
→
Specify the oxidation numbers of the metals in the following coordination entities:
i. $\left[ Co \left( H _2 O \right)( CN )( en )_2\right]^{2+}$
ii. $\left[ Pt ( Cl )_4\right]^{2-}$
iii. $K _3\left[ Fe ( CN )_6\right]$
iv. $\left[ Cr \left( NH _3\right)_3 Cl _3\right]$
→
$(a).$ Using, Valence Bond Theory identify $A, B, C, D, E$ and $F$ in the following table:
Image
$(b).$ Write the ionic equations for the reaction of acidified $K_2Cr_2O_7$ with
$(i) \ H_2S$ and $(ii) \ FeSO_4$
→
Answer the following questions.
Write chemical reaction to show that glucose contains aldehyde as carbonyl group.
→
How to determine the vapour pressure and total pressure of the components in binary solution of two volatile liquids? Explain their mathematical form and also explain the graph between mole fraction and vapour pressure for an ideal solution.
→
  1. Define the following terms:
  1. Mole fraction.
  2. Ideal solution.
  1. $15.0\ g$ of an unknown molecular material is dissolved in $450\ g$ of water. The resulting solution freezes at - $0.34^\circ\ C$. What is the molar mass of the material?
($K_f$ for water = $1.86\ K\ kg\ mol^{–1}$).
→
Explain the elimination reaction of haloalkanes.
→
Giving an example for each describe the following reactions:
i. Hofmann bromamide reaction.
ii. Gattermann reaction.
iii. Coupling reaction.
→