P- BLOCK ELEMENTS
•Group-15 Elements
•Group-16 Elements
• 17th group elements
•18 th group elements
1. Which of the following elements does
not belong to group 15?
a) Nitrogen
b) phosphorus
c) Arsenic
d) Tin
Group -15 elemets are; N, P, As,Sb & Bi.
Tin ,Sn:Group-14 element.
Answ: (d)
2. Which is the correct order regarding the
boiling points of hydrides of Group 15?
a) NH3> PH3> AsH3
b) NH3< PH3< AsH3
c) NH3> PH3< AsH3
d) NH3< PH3> AsH3
B. pt. increases with strength of
intermolecular forces, which is in the
order: PH3< AsH3< SbH3< NH3< BiH3.
Answ: c)
3. Covalency of nitrogen never exceeds
a) 3
b) 4
c) 5
d) 6
Nitrogen has only four orbitals in its
valence shell, all of which can be used
for bond formation. No d- orbitals are
available.
Answ: (b)
4. Which of the following orders regarding
H—E—H bond angle of the hydrides of group
15 elements is correct?
a) H-N-H > H-P-H> H-As-H
b) H—N—H < H—P—H< H—As—H
c) H-N-H > H-P-H< H-As-H
d) H—N—H < H—P—H> H—As—H
As electronegativity C.A dereases bond angle
decreases.
Answ: (a)
5. Which of the following oxides of nitrogen
are obtained on heating Ammonium nitrate?
a) N2O
b) NO
c) NO2
d) N2O5
NH4NO3 heat N2O +2H2O.
Answ: (a)
6. Orthophosphorous acid is a
a) monobasic acid
b) dibasic acid
c) tribasic acid
d) tetrabasic acid.
H3PO4 has 2 P—OH bonds. The H
atoms bonded to O are responsible
for the basicity of the acid.
Answ: (b)
7. Concentrated nitric acid oxidizes iodine to
a) HI
b) HIO3
c) NH4I
d) HIO4
I2 +10HNO3  2HIO3 +10NO2 +4H2O
Answ: (b)
8. Which of the elements of Group 16 has
maximum tendency of catenation?
a)Oxygen
b)Sulphur
c)Selenium
d)Tellurium
S—S bond is strongest among group 16
elements. So it shows maximum
extent of catenation.
Answ: (b)
9. Which of the following hydrides of
Group 16 has the lowest boiling point?
a) H2O
b)H2S
c)H2Se
d)H2Te
B. pt. increases with strength of
intermolecular forces. H2O has strong
intermolecular hydrogen bonds. In case of
H2S, H2Se &H2Te, weak dispersion forces :
increases with M.
Answ: (b)
10. Which of the following bonds has
the highest bond energy?
a) O—O
b) S—S
c) Se—Se
d) Te—Te
O—O bond though shortest, but weak
due to strong lone pair- lone pair
repulsions due to the small size of O
atoms.
Answ: (b)
11. Which of the following is the
weakest acid?
a) H2S
b) H2Se
c) H2O
d) H2Te
H2O has the strongest bond which
doesn’t break readily to release H+. So
it is the weakest acid.
Answ: (c)
12. In the manufacture of sulphuric acid by
the contact process, SO3 is not added to
water directly to form H2SO4 because
a) the reaction does not go to completion.
b) the reaction is exothermic.
c) the reaction is quite slow.
d) SO3 is insoluble in water.
Ans (b)
13. Which of the following forms of
sulphur is stable at room temperature
and 1 atmospheric pressure?
a) Amorphous
b) hexagonal
c) Monoclinic
d) Orthorhombic
Rhombic sulphur ( α sulphur), Above
369K,monoclinic form is stable.
Answ:( d)
14. Sulphur dioxide is a strong reducing
agent. However, it can also act as an
oxidizing agent. Which of the following
reactions shows its oxidizing natures?
a) Bleaching flower petals.
b) Decolorizing of acidified KMnO4 solution.
c) Reaction of H2S to give sulphur.
d) Turning acidified dichromate paper green.
Answ: (c)
15. When conc. H2SO4 is added to NaCl
a) Cl— is released as volatile HCl.
b) Cl— is oxidized to Cl2.
c) NaCl is dehydrated.
d) NaCl is neutralized by H2SO4.
Due to low volatility of H2SO4
2NaCl + H2SO4  2HCl + Na2SO4
Answ:( a)
16. Which of the following orders of bond
dissociation enthalpy of halogens is
correct?
a) F—F > Cl—Cl > Br—Br
b) F—F < Cl—Cl < Br—Br
c) F—F > Cl—Cl < Br—Br
d) F—F < Cl—Cl > Br—Br
Small size of F; l.p l.p repulsion
Answ: (d)
17. Which of the following orders of
melting point of hydrides of halogens is
correct?
a) HF > HCl > HBr
b) HF < HCl < HBr
c) HF > HCl < HBr
d) HF < HCl > HBr
In HF –Strong H-bonding, in others weak
dispersion forces.
Answ: (c)
18. The structure of IF7 is
a) Planar
b) Distorted octahedral
c) Pentagonal bipyramidal
d) Distorted trigonal pyramidal
Here 7 bond pairs & no lone pairs;
Hence according to VSEPR pentagonal
bipyramidal.
Answ: (c)
19. The anhydride of HClO4 is
a) ClO4-b) Cl2O7
c) ClO2
d) ClO3
Removal of one molecule of H2O
from two molecules of HClO4 gives
Cl2O7
Answ: (b)
20. Which of the following interhalogens
does not exist?
a) ClF
b) ClF2
c) ClF3
d)ClF5
The inter halogen compounds have a
general molecular formula of XX’2n+1 (n= 0,
1, 2 or 3). ClF2 doesn’t fit to in to it.
Answ(b)
21. The order of Acidic strength of oxo
acids of chlorine is
a) HClO < HClO2 < HClO3 < HClO4
b) HClO > HClO2 > HClO3 > HClO4
c) HClO > HClO2 > HClO3 < HClO4
d) HClO < HClO2 < HClO3 > HClO4
Acidic strength increases with Oxdn state
of Cl
Answ: (a)
22. The structure of XeO4 is
a) square planar
b) tetrahedral
c) pentagonal with one lone pair of
electrons
d) octahedral with two lone pairs
No l.p but 4 b.p are there ; structure is
tetrahedral.
Answ: (a)
23. The ionization energy of
Xe  Xe+ + e—is very close to that of
a)N2  N2+ + e— b) O2  O2+ + e—
c) C2 C2+ + e—
d) B2  B2+ + e—
Answ: (b)
24. The number of electron pairs
around Xe in XeF4 are
a) 3
b) 4
c) 5
d) 6
In XeF4, out of 8 electrons of Xe 2 l.p &
2b.p: & 2 b.p of F is also presnt .
Total 6 pairs.
Answ: (b)
25. When chlorine reacts with cold and
dilute solution of sodium hydroxide, the
products obtained are
a) Cl— + ClO—
b) Cl—+ ClO2—
c) Cl—+ ClO3—
d) Cl— + ClO4—
2 NaOH + Cl2  NaCl + NaOCl +H2O.
Answ: (a)
26. The structure of interhalogen AX3 is
a) Triangular planar b) Pyramidal
c) T-shaped with two lone pairs of
electrons at two equilateral positions
d) Tetrahedral with single electron.
AX3 contains 3 b.p and 2l.p, hence structure
is T-shaped with two lone pairs of electrons
at two equilateral positions
Answ: (c)
27. Which of the following represents
hypohalous acid?
a) HOX
b) HXO2
c) HXO3
d) HXO4
Answ: (a)
28. Which of the following statements
regarding ozone is not true?
a) Ozone is an allotrope of oxygen.
b) The ozone layer protects the earth’s surface
from an excessive concentration of harmful
ultraviolet radiation.
c) The conversion of oxygen into ozone is an
exothermic process.
d) Ozone is much more powerful oxidizing
agent
than molecular oxygen. Answ: (c)
29. The dimerization of NO2 is accompanied
by
a) an increase in paramagnetism
b) a decrease in paramagnetism
c) no change in paramagnetism
d) a darkening in colour
Dimerisation of NO2 is : 2NO2  N2O4. The
odd electron of NO2 gets paired up &
decrease the paramagnetism.
Answ: (b)
30. Phosphine may be produced by
adding water to
a) Ca3P2
b) P4O6
c) P4O10
d) HPO3
Ca3P2 + 6H2O  3 Ca (OH)2+ 2 PH3
Answ: (a)
31. Which of the following possesses pπ-d π
bonding?
a) NO3—
b) BO33c) SO32d) CO32SO32- is –O- S=O
–O
π bond is d-orbitals of S & p- orbitals of O
N, B, & C do not have d-orbitals
Answ: c)
32. Which of the following is the order of
compounds is according to the decreasing
order of the oxidation state of nitrogen?
a) HNO3 ,NO,NH4Cl,N2
b) HNO3 , NO, N2 , NH4Cl
c) HNO3 , NH4Cl , NO, N2
d) NO, HNO3 , NH4Cl,N2
O.S of N in HNO3 : +5, NO : +2, N2 : 0,
NH4Cl: -3
Answ: (b)
33. Smallest bond angle is in
a) NCl3
b) AsCl3
c) SbCl3
d) PCl3
Down the group at.size of central atom
increases; bond angle decreases.
Answ: (c)
34. The gas used for inflating aero plane
tyres is
a) H2
b)He
c) N2
d) Ar
He is light & non flammable
Answ: (b)
35. Xenon best reacts with
a) F2
b) O2
c) N2
d) Cl2
F is most electronegative element
Answ: (c)
36. Among known interhalogens the
maximum number of halogen atoms in a
molecule, is
a) 8
b) 7
c) 5
d) 6
Answ: (a)
37. The halogen(s) which can displace iodine
from KI is/ are
a) F
b) Cl
c) Br
d) All these
Answ: (d)
38. Elements of which one of the following
groups will form anions most readily?
a) Group -16
b) Group -15
c) Group -17
d) Group -18
Answ: (c)
39. Bleaching action of chlorine is due to
a) Oxidation
b) reduction
c) Hydrolysis
d) hydration
Chlorine water  HCl+HOCl [O]
Answ: (a)
40. Among the following molecules
i) Xe O3 ii) XeO F4 iii) Xe F6, Those having
same number of lone pairs on Xe are
a) (i) and ii) only
b) (i) and iii) only
c) (ii) and (iii) only d) (i), ii) and (iii) only
Answ: (d)
41. Which of the following is not correct?
a) Xe O3 Has four σ and four π bonds.
b) The hybridisation of Xe in Xe F4 is
sp3d2.
c) Among the noble gases the occurrence
of Ar is highest in air.
d) Liquid he is used in cryogenic liquids.
Answ: (a)
42. Xe F6 on complete hydrolysis gives
a) Xe
b) Xe O2
c) Xe O3
d) Xe O4
Xe F6 + 3 H2O  6HF + Xe O3
Answ: (c )
43. Which of the following sets has
strongest tendency to form anions?
a) Ga,In,Tl b) Na,Mg, Al
c) N,O,F
d) V,Cr, Mn.
N,O,F has highest electron affinity:
Forms anions redily.
Answ: (c )
44. Which of the following bonds will be
most polar?
a) N-Cl
b) O-F
c) N-F
d) N-N
Greater the electronegative difference
more is the polarity.
Answ: (c )
45. Chorine gas is dried over
a) Quick lime
b) caustic soda
c) Caustic potash d) conc H2SO4
conc H2SO4, All others reacts with chlorne.
Answ: (d )
46. When cold NaOH reacts with which
of the following is formed?
a) NaClO
b) NaClO2
c) NaClO3
d) None
2NaOH+ Cl2  NaCl + NaOCl + H2O
Answ: (a)
47. A colour less gas with smell of rotten
fish is
a) H2S
b) PH3
c) SO2
d) None of these.
Answ: (b)
48. On heating O3,its volume becomes
a) Half
b) double
c) 2/3 times
d) 3/2 times.
2O3 3O2
2vol  3 vol.
Answ: (d)
49. Which on of the following is not
oxidised by ozone?
a) FeSO4
b) KMnO4
c) KI
d) K2MnO4
Mn in has highest oxidationstate +7;
furter oxidation is not possible.
Answ: (b)
50. Phosphine is prepared in the
laboratory by
a) Heating P in a current of H2
b) Heating yellow P with aq KOH
c) Heating red P with aq KOH
d) treating yellow P with NH3
Answ: (b)
51. Helium is added to oxygen used by sea
divers because it is
a) Practically not soluble in blood at high
pressure.
b) Lighter than nitrogen
c) Readily miscible with oxygen
d) Less poisonous than nitrogen.
Answ: (a)
52. Compound(s) possible with xenon
is/are
a) Oxides
b) flurides
c) Oxyflurides
d) All of these.
Xe forms compounds with highly
electronegative elements.
Answ: (d)
53. Sulphuric acid behaves as
a) A strong acid
b) An oxidising agent
c) Adehydrating agent d) All of these
Answ: (d)
54. Among halogens electron gain
enthalpy is maximum in
a) F
b) I
c) Br
d) Cl
Answ: (d)
55. The ammonia molecule
a) Triangular planar
b)triangular bipyramidal
c) Regular tetrahedron with bond angle
109o28’
d) Trigonal pyramidal
Answ: (d)
56. With excess water PCl5 gives
a) H3PO4 + HCl
b) H3PO3 + HCl
c) H3PO2 + HCl
d) H4P2O7 + HCl
PCl5 +4 H2O H3PO4 + 5HCl
Answ: (a)
57. The catalyst used in the contact
process is
a) Fe2O3
b) V2O5
c) SO3
d) Ag2O
Answ: (b)
58. Which of the following is a
radioactive halogen?
a) Cl
b) Br
c) I
d) At
Answ: (d)