Download App

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

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements5 Marks
Question
  1. Give reasons for the following:
i. $Mn ^{3+}$ is a good oxidizing agent.
ii. $E ^{\circ} m ^{2+} / M$ values are not regular for first row transition metals. (3d series)
iii. Although ' $F$ ' is more electronegative then ' O ', the highest Mn fluoride is $Mnf _4$, whereas the highest oxide is $Mn _2 O _7$.
  1. Complete the following equations:
$\text{2CrO}_{4}^{2}+\text{2H}^{+}\rightarrow$

$\text{KMnO}_{4}\xrightarrow{heat}$
✓

Answer

  1.  
i. $Mn ^{3+}\left(3 d^4\right)$ good electron acceptor as resulting species is more stable $\left(3 d^5\right)$
ii. The $E^{\circ}\left( M ^{2+} / M \right)$ values are not regular which can be explained from the irregular variation of ionisation enthalpies $\left(\Delta iH _1+\Delta i H _2\right)$, sublimation enthalpies and hydration enthalpies.
iii. Due to multiple bond formation ability of oxygen with Mn in $Mn _2 O _7$.
  1.  
  1. $2CrO_4^{2-} + 2H^+ \rightarrow Cr_2O_7^{2-}+ H_2O.$
  2. $2KMnO_4$​​​​​​​ $\xrightarrow{Heat} K_2MnO_4 + MnO_2 + O_2.$

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. A $10\%$ solution (by mass) of sucrose in water has a freezing point of $269.15 K$. Calculate the freezing point of $10\%$ glucose in water if the freezing point of pure water is $273.15 K$. Given:
(Molar mass of sucrose = $342 g mol^{-1}$)

(Molar mass of glucose = $180 g mol^{-1}$)
  1. Define the following terms:
  1. Molality (m)
  2. Abnormal molar mass
→
Explain the following :
(i) Fermentation
(ii) Dehydration
(iii) Hydrogen bonding in alcohols.
→
i. Name the element of 3d transition series which shows maximum number of oxidation states. Why does it show so?
ii. which transition metal of 3 d series has positive $E ^{\circ}\left( M ^{2+} / M \right)$ value and why?
iii. Out of $Cr ^{3+}$ and $Mn ^{3+}$, which is a stronger oxidizing agent and why?
iv. Name a member of the lanthanoid series which is well known to exhibit +2 oxidation state.
v. Complete the following equation:
$MnO_4^{-}+8 H^{+}+5 e^{-} \rightarrow$
→

Identify $A$ to $E$ and also explain the reactions involved.
→
$[A], [B], [C], [D], [E], [F]$ and $[G]$ are amines each of which forms a hydrochloride containing $32.42\%$ chlorine. $[A], [B], [C]$ and $[D]$ evolve $N_2$ on reaction with $HNO_2,$ but $[E], [F], [G]$ and $[H]$ do not. Give structures of $[A]$ to $[H]$ with reasons.
→
Write the $S _{ N } 2$ mechanism of bimolecular nucleophilic substitution.
→
What is the role of adsorption in heterogenous catalysis?
→
Discuss aldol condensation in detail.
→
Image
→
What is crystal field splitting energy? How does the magnitude of $\Delta_0$ decide the actual configuration of d-orbitals in a coordination entity?
→