Important P block Questions Class 12th Chemistry

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Important P block Questions Class 12th Chemistry...

P-Block Questions.

(i) Draw the structure of phosphinic acid (H3PO4)
(ii) Write a chemical reaction for its use as reducing agent.
Answer the following :
(i) Which neutral molecule would be isoelectronic with ClO- ?
(ii) Of Bi(V) and Sb(V) which may be a stronger oxidising agent and why ?
(iii) Draw the structures of white phosphorus and red phosphorus. Which one of these two types of phosphorus is more reactive and why?
(iv) What is the oxidation number of phosphorus in H3PO2 molecule ?
Q3. Complete the following chemical equations:
F2 + H2O ( _____________
Ca3P2 + H2O   ( _____________
XeF4 + H2O   ( _____________
O3 + I- + H2O (______________
P4 + NaOH + H2O ( ___________
I- + H2O + O3 ( _____________
XeF2 + PF5 (______________
Cl2 + NaOH ( ______________
PCl5 + H2O ( ________________
F2 + H2O ( ______________
SO2 + MnO4- + H2O ( _____________
HgCl2 + PH3 ( ______________
Cu + HNO3 ( ______________
NaOH + Cl2 ( ______________
XeF6 + H20 (_____________
P4 + SO2Cl2 ( ______________
I2 + HNO3 ( ______________
Q.4 Write the structural formulae of the following compounds :
BrF3
XeF2
H2S2O8
HClO3
HClO4
H3PO2
N2O5
XeOF4
H2S2O7
NO3-
H3PO4
PCl5
SO32-
H4P2O5
XeF4

Q.5 Assign a reason for each of the following situations :
Phosphorus shows marked tendency for catenation but nitrogen shows little tendency for catenation.
The electron gain enthalpy with negative sign for oxygen (-141 kJ mol-1) is numerically less than that for sulphur (-200 kJ mol-1).
In the structure of HNO3 molecule, the N—O bond (121 pm) is shorter that N—OH bond (140 pm).
SF4 is easily hydrolysed whereas SF6 is not easily hydrolysed.
XeF2 has a straight linear structure and not a bent angular structure.
NH3 is a stronger base than PH3.
Sulphur has a greater tendency for catenation than oxygen.
Bond dissociation energy of F2 is less than that of Cl2.
Fluorine does not exhibit any positive oxidation state.
The majority of known noble gas compounds are those of Xenon.
Phosphorus is much more reactive than nitrogen.
Why is red phosphorus less reactive than white phosphorus ?
All the P—Cl bonds in PCl5 are not equivalent.
ICl is more reactive than I2.
Phosphorus (P4) is more reactive than nitrogen (N2).
All the bonds in PCl5 are not equal in length.
Sulphur in vapour state exhibits paramagnetism.
Bond angle in PH3 molecule is lesser than that in NH3 molecule?
No chemical compound of Helium is known.
The electron gain enthalpy of sulphur atom has a greater negative value than that of oxygen atom.
Nitrogen does not form pentahalides.
In aqueous solutions, HI is a stronger acid than HCl.
The negative value of electron gain enthalpy is less for fluorine than that for chlorine.
Hydrogen fluoride has a much higher boiling point than hydrogen chloride.
Ammonia has a higher boiling point than phosphine.
+3 oxidation state becomes more and more stable from As to Bi in the group.
In the solution of H2SO4 in water, the second dissociation constant Ka2, is less than the first dissociation constant Ka1.
Fluorine is a stronger oxidising agent than chlorine.
The +5 oxidation state becomes less stable down the group in group 15 of the periodic table.
H2O is a liquid while, inspite of a higher molecular mass, H2S is a gas.
Iron dissolves in HCl to form FeCl2 and not FeCl3.
Helium is used in diving equipment.
Why does NO2 dimerise?
The value of electron gain enthalpy with negative sign for sulphur is higher than that for oxygen.
NF3 is an exothermic compound but NCl3 is endothermic compound.
ClF3 molecule has a T-shaped structure and not a trigonal planar one.
The stability of +5 oxidation state decreases down the group in group 15 of the periodic table.
Solid phosphorus pentachloride behaves as an ionic compound.
Halogens are strong oxidizing agents.
XeF2 is a linear compound without a bend.
Nitrogen is relatively inert as compared to phosphorus.
Fluorine never acts as the central atom in polyatomic interhalogen compounds.
Nitrogen shows weaker tendency for catenation than phosphorus.
H2S is less acidic than H2Te.
Oxygen is involved in hydrogen bonding while chlorine is not.
Unlike other halogens, fluorine forms only one oxoacid, HOF.
SF6 is kinetically an inert substance.
F2 is most reactive compound of all the four common halogens.
The acidic strength decreases in the order HCl>H2S>PH3.