Download App

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

Bihar BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements2 Marks
Question
(A) why are transition elements good catalysts ?
(B) Zinc does not exhibit variable oxidate state, why?
✓

Answer

(A) Transition elements and their compounds are effective catalysts due to:
- Variable Oxidation States: They can change oxidation states to form unstable intermediate complexes with reactants.
- Large Surface Area: They provide a platform for reactants to be adsorbed, increasing the local concentration and lowering the activation energy.
(B) Zinc ( $Z=30$ ) has a ground state electronic configuration of $[A r] 3 d^{10} 4 s^2$. It does not show variable oxidation states because:
- Completely Filled $d$-subshell: The $3 d^{10}$ configuration is highly stable.
- Involvement of only s-electrons: Only the two electrons from the $4 s$ orbital are lost to form the $Z n^{2+}$ ion. The stable $3 d^{10}$ electrons do not participate in bonding under normal conditions.

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 "Short Answer Type Questions [2M]" from The d & f Block Elements→The d & f Block Elements — all question types→Chemistry STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

Explain three differences between the rate constant of reaction and rate of a reaction.
→
How do antiseptics differ from disinfectants? Give one example of each.
→
Differentiate between conformation and configuration in open chain molecules by giving one example each.
→
Give the structures of A, B and C in the following reaction:

$\text{C}_6\text{H}_5\text{N}_2\text{Cl}\xrightarrow[]{\text{CuCN}}\text{A}\xrightarrow[]{\text{H}_2\text{O}/\text{H}^+}\text{B}\xrightarrow[\Delta]{\text{NH}_3}\text{C}$

→
To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.
→
What will be the correct order for the wavelength of absorption in the visible region for the following :
$\left[ Ni \left( NO _2\right)_6\right]^{4-},\left[ Ni \left( NH _3\right)_6\right]^{2+},\left[ Ni \left( H _2 O \right)_6\right]^{2+} ?$
→
Determine the values of equilibrium constant (KC) and $\Delta$Go for the following reaction:
$\text{Ni (s)}+\text{2Ag}^{+}\text{(aq)}\rightarrow\text{Ni}^{2+}+\text{2Ag(s)},\text{E}^{o}=1.05\text{V}\ \ \ (\text{IF} = 96500 \text{C mol}^{–1}).$
→
Give examples of the common names of carboxylic acid which are derived from Latin or Greek names of their natural sources.
→
Identify the compounds A, B and C in the following reaction.
$\text{CH}_3-\text{Br}\xrightarrow{\text{Mg}/\text{ether}}\text{(A)}\xrightarrow[(\text{ii})\text{Water}]{(\text{i})\text{CO}_2}\text{(B)}\xrightarrow[\triangle]{\text{CH}_3\text{OH/}\text{H}^+}\text{(C)}$
→
Explain the Tollens' test to distinguish aldehydes from ketones with equation. ### Write a note on silver mirror test.
→