Explain why:
(i) Transition elements form coloured compounds.
(ii) Interhalogen compounds are more reactive than their constituent elements.
(iii) Cu+ is diamagnetic but Cu2+ is paramagnetic. (Z = 29).
(i) Due to the presence of unpaired electrons in d-orbitals and empty d-orbitals. Gives rise to possibility of d-d transition.
(ii) X—Y bonds are weaker than X—X and Y—Y bonds/Polar nature of X—Y bonds/Less overlapping of orbitals in X—Y bond.
(iii) Cu1+ has no unpaired electrons, hence diamagnetic. Cu2+ has unpaired electrons, hence paramagnetic. [Cu→29→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 4s1 , 3d10]
[Cu1+→28→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 3d10; d-orbital fully filled]
all electron in Cu1+ is paired.
[Cu2+→27→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 4s1 , 3d9 ; d-orbital partially filled 1 unpaired electron].
Fill in the blanks by choosing the appropriate word/words from those given in the
brackets:
(increases, decreases, positive, efficient, 68, non-efficient, no α-hydrogen, α-hydrogen,
negative, Rosenmund’s, greater, Cannizzaro, 74, common-ion effect, lesser, buffer
action, diamagnetic, paramagnetic)
(i) The more__________ the standard reduction potential of a metal, the ________ is
its ability to displace hydrogen from acids.
(ii) Both ccp and hcp are ____________ packings and occupy about _________% of
the available space.
(iii) Solubility of silver chloride _____________ in the presence of sodium chloride
because of _____________.
(iv) Benzaldehyde undergoes ___________ reaction on treatment with concentrated
sodium hydroxide because it has ___________ atom.
(v) The transition metals show ______________ character because of the presence of
unpaired electrons and Cu+ is _____________because its electronic configuration
is [Ar]3d10.
negative, greater
,efficient, 74
,decreases, common-ion effect
,Cannizzaro, no α- hydrogen
,paramagnetic, diamagnetic
Match the following:
| A. Disaccharide | (i) Lucas reagent |
| B. Carbylamine | (ii) Condensation polymer |
| C. Dacron | (iii) Obnoxious smell |
| D. Dacron | (iv) Sucrose |
| E. Anhydrous ZnCl2 + conc. HCl | (v) Hexaamminecobalt(III)ion |
A. Disaccharide | (i) Sucrose |
B. Carbylamine | (ii) Obnoxious smell |
C. Dacron | (iii) Condensation polymer |
D. Dacron | (iv) Hexaamminecobalt(III)ion |
E. Anhydrous ZnCl2 + conc. HCl | (v) Lucas reagent |
In the extraction of zinc from zinc how oxide is converted to zinc.
(i) Give an equation to show how zinc oxide is converted to zinc.
(ii) How is impure zinc finally electro-refined.
(i)ZnO+C → Zn+CO
(ii) Impure zinc is electro-refined by using impure zinc as an anode, pure zinc as a cathode and an aqueous solution of ZnSO4 as electrolyte containing a little H2SO4.
Cathode → Zn2+ + 2e- → Zn
Anode → Zn → Zn2+ + 2e‒
In the cyanide process the following steps are envolved.
(i) Concentration: The powdered cyanide ore is concentrated by froth flotation process.
(ii) Treatment with sodium cyanide: The concentrate ore is treated with dilute solution of sodium cyanide. A current of air is constantly passed through the solution. After few hours soluble complex of sodium argento cyanide is formed.
Air supplied during the reaction oxidises sodium sulphide to sodium sulphate, so the reaction proceeds in forward direction.
2Na2S +2O2 +2H2O ----> Na2S2O3 +2NaOH
Na2S2O3 +2NaOH 2 O2 -----> 2Na2SO4 +H2O
(iii) Precipitation of silver : The solution obtained after above step is filtered and treated with scrap zinc to precipitate silver.
2Na[Ag(CN)2 +Zn -----> Na2[Zn(CN)4] +2Ag
sodium tetra cyanozincate
Zinc displaces silver from the complex because it is more electroposetive than silver.
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