P – BLOCK ELEMENTS MCQs- 5
1) A solution containing NH4Cl and NaNO2 on boiling produces
a) Nitrogen peroxide
c) Nitrous oxide
2) The stable halide of nitrogen is
3) In NH3 and PH3 the common property is their
c) Basic nature
d) None of these
4) Carbon monoxide acts as a Lewis base because it has
a) A double bond between C and O atoms
b) A triple bond between C and 0 atoms
c) A lone pair of electrons on the C atom
d) Two lone pairs of electrons on the 0 atom
5) U.V. rays can be checked by
a) Flint glass
b) Soda glass
c) Pyrex glass
6) Lead pipes can be used safely for carrying
a) Soft water
b) Soft water first treated with lime stone
d) Soft as well as hard water
7) Producer gas is a mixture of
c) CO + water vapours
8) A gas burns with a blue flame and reduces hot copper oxide to copper metal. When burnt in oxygen, It produces a gas which turns lime water milky. The original colourless gas is
9) Carbon monoxide is absorbed by
a) Ammoniacal cuprous chloride solution
b) Pyrogallol solution
d) Carbon tetrachloride
10) The poisonous gas which combines with the haemoglobin of the blood to form carboxyhaemoglobin is
11) Dry ice is
12) Which of the following has giant covalent structure ?
13) Which of the following is used as an oxidising agent in the laboratory ?
a) Lead acetate
b) Basic lead acetate
c) Basic lead carbonate
d) Lead tetraacetate
14) When tin is boiled with alkali solution, the product is
15) Tin reacts with conc. HNO3 to form
a) Metastannic acid
b) Tannic nitrate
c) Stannous nitrate
d) Tin stone
16) Which of the following compounds would you expect to be most ionic in character ?
17) Which of the following statements is not true ?
a) Lead is a true metal with + 2 electrovalency
18) Which of the following statements is not true ?
19) Sandhur used by women is an oxide of lead with the formula
20) White lead is formed when one of the following is added to the solution of any lead salt:
b) Dil HCI
d) Dil. NaOH
21) Which of the following gases, if present in the atmosphere, darkens the surface painted by white lead?
22) Chrome yellow is
23) In silicates, silicon is
c) sp- Hybridized
24) Glass is a homogeneous mixture of
a) Boron and silicon carbides
b) Carbonates of alkali and alkaline earth metals
c) Oxides of alkali and alkaline earth metals
d) Different silicates and borates
25) Lead is most readily dissolved in
26) Water transported through lead pipes becomes poisonous due to the formation of
27) The phenomenon by which activated charcoal removes colouring matter from pure substances is
28) Which oxidation state is not shown by carbon in its compounds ?
29) In which of the following is there a p-d bonding ?
30) Which of the following is used in making printers ink, shoe polish, black varnish and paint?
a) Bone black
b) Carbon black
c) Gas black
d) Lamp black
31) Which of the following is most electronegative ?
32) A higher percentage of carbon is found in
33) The percentage of lead in lead pencils is
34) CCI4 is used as a fire extinguisher because
a) Its m.p. is high
b) It forms covalent bond
c) Its b.p. is low
d) It gives incombustible vapours
35) The correct order of increasing C—O bond length for is
36) The shape of gaseous SnCI2 is
37) The most stable +2 oxidation state is exhibited by
38) Mark the oxide which is amphoteric in character:
39) RRR PbF4, PbCI4 exist but PbBr4 and Pbl4 do not exist because of
40) The most stable allotrope of carbon at high temperatures is
41) The type of hybridization involved in the recently discovered allotrope of carbon (e.g., C60 or fullerene) is
42) The correct order of increasing extent of hydrolysis in the following is
43) Which element-element bond has the highest bond energy ?
a) Sn – Sn
b) Ge – Ge
44) Dry powder fire extinguisher contains
c) Sand and baking soda
45) Drikold is
b) Ether and dry ice
c) Dry ice and alcohol
d) Dry ice and acetone
46) Carbon is soluble in
a) Conc. HCI
d) Dil. HCI
47) If a person is injured by the shot of a gun and all the pellets could not be removed, it may cause poisoning with
48) In the sale of diamonds the unit of weight is carat. One carat is equal to
c) 400 mg
d) 200 mg
49) Aqua dag is a suspension of ……… in water.
a) Lamp black
50) Carbon dioxide is isostructural with
51) CO2 is isostructural with
52) Which of the following are amphoteric ?
53) Which of the following statement(s) is/are true?
a) The lattice structure of diamond and graphite are different
b) Graphite conducts electricity while diamond does not
c) Graphite has lower density than diamond
d) All the above
54) Graphite is
a) a good conductor of heat
b) Softer than diamond
c) Used for making lubricants
d) All the above
55) The reactivity of NO is due to
a) Its low molecular weight
b) Its gaseous state
c) its odd electron
56) Nitrogen is an essential constituent of all
c) Proteins and fats
d) None of these
57) Which among the following forms the most basic oxide ?
58) Which phosphorus is used as rat poison ?
59) The basicities of the acids H3PO2, H3PO4 and H4P2O7 are respectively
a) 1, 2, 3, 7
b) 2, 3, 4, 7
c) 1, 2, 3, 4
d) 1, 2, 3, 5
60) Red phosphorus is less reactive than yellow phosphorus because
a) It is red in colour
c) It is hard
d) It is highly polymerised
61) Which of the following are fertilizers ?
I. Calcium ammonium nitrate
III Calcium cyanamide
IV. Super phosphate
a) I and II
b) I and III
c) I, II and III
62) The gas obtained on heating ammonium nitrite is
63) Phosphorus trioxide on reaction with water yields
a) Phosphoric acid
b) Pyrophosphoric acid
c) Phosphorous acid
d) Mixture of phosphorous acid and pyrophosphoric acid
64) The heat of formation of an explosive compound like NCl3 is
d) Positive or negative
65) Which of the following is more acidic ?
66) The structure of PCl5 is
b) Trigonal bipyramidal
67) P4O10 reacts with water to give
a) Hypophosphorus acid
b) Orthophosphorus acid
c) Hypophosphoric acid
d) Orthophosphoric acid
68) Which of the following compounds are not stable ?
d) b and c
69) Which is a basic oxide ?
70) O2, N2 are present in the ratio of 1 : 4 by weight. The ratio of number of molecules is
a) 4 : 1
b) 1 : 4
c) 2 : 1
d) 7 : 32
71) One of the acids given below is formed from P2O3 and the rest are formed from P2O5. The acid formed from P2O3 is
72) Which of the following is not correct ?
a) White and red phosphorus react equally with chlorine at room temperature
b) White phosphorus is metastable, while red phosphorus is stable
c) White phosphorus is lighter than red phosphorus
d) White phosphorus is highly poisonous, while red phosphorus is not
73) PH4I reacts with NaOH to form
74) How is NH3 generally manufactured for fertilizers ?
75) The N-H bond in NH3 is
76) Red phosphorus is less reactive, less volatile and soluble specially in non-polar solvents because
a) It has less molecular energy
b) It has high molecular energy
c) It possesses a highly polymerised structure
d) It forms condensation products
77) White P is more reactive than nitrogen because the
a) Electronegativity of P is low
b) lonisation energy of P is low
78) Nitric oxide may be prepared by
79) Ammonia water makes a good cleaning agent because it
a) Is weakly basic
b) Emulsifies grease
c) Leaves no residue when wiped off
d) All are true
80) The structure of phosphide ion is similar to that of
c) Nitride ion
81) Which of the following is used in the preparation of chlorine ?
82) The acidity of the following acids is in the order
83) Which does not form interhalogen compounds?
d) All are correct
84) Which is the correct order of basic strength ?
85) Iodine gives a blue colour with
86) Which of the following is not characteristic of interhalogen compounds ?
a) They are more reactive than halogens
b) They are quite unstable, but none of them is explosive
c) They are covalent in nature
d) They have low boiling points and are highly volatile
87) The bond angle in the chlorine molecule is
88) What is the minimum number of moles of NaOH which would be needed to absorb one mole of Cl2 ?
89) Which of the following reacts with H2 in the dark?
90) Which of the following species would you not expect to oxidise?
91) A positive chromyl chloride test is given by a salt containing
92) Which of the following statements is correct?
a) All halogens except fluorine form oxyacids
b) Only chlorine and bromine form oxyacids
c) All halogens form oxyacids
d) Only iodine forms oxyacids
93) Which of the following solutions has the maximum pH ?
94) The bond in a molecule of HCl is formed due to the overlapping of
a) s- and p- orbitals
b) s- and sp- orbitals
c) p- and p- orbitals
d) None of these
95) The outer configuration of a halide ion is
96) A gas reacts with CaO, but not with NaHCO3. The gas is
97) A greenish yellow gas reacts with an alkali metal hydroxide to form a halate, which can be used in fire works and safety matches. The gas and halate respectively are
98) The number of p-electrons in a bromine atom is
99) The halogen used in the preparation of insecticides is
100) The least bond dissociation energy is possessed by
Ans 1) d
Ans Desc 1) NH4Cl + NaNO2 NaCl + 2H2O + N2.
Ans 2) d
Ans Desc 2)
Ans 3) c
Ans Desc 3) Both NH3 and PH3 are basic in nature but NH3 is more basic than PH3.
Ans 4) c
Ans Desc 4) Carbon monoxide has the structure : C = 0 : . It forms a metal-carbon bond and thus donates its lone pair on carbon to the metal in metal carbonyls and behaves as a Lewis base.
Ans 5) d
Ans Desc 5) U.V. rays can be absorbed by Crookes glass due to the presence of CeO2 in it.
Ans 6) b
Ans Desc 6) Soft water first treated with lime stone (CaCO3) contains some dissolved CO2 –3 ions in it which can form a coating of insoluble lead carbonate on the surface of lead pipe and protects it from further action.
Ans 7) a
Ans Desc 7) Producer gas is a mixture of CO and N2.
Ans 8) b
Ans Desc 8) CO burns with a blue flame and reduces hot copper oxide to Cu metal
CuO + CO Cu + CO2
CO on burning in oxygen produces CO2 which turns lime water milky due to the formation of CaCO3 (insoluble)
2 CO + O2 2 CO2
Ca (OH)2 + C02 CaC03 + H2O
Ans 9) a
Ans Desc 9) Ammoniacal solution of CuCI absorbs CO due to the formation of the complex ion
[Cu CO NH3]+.
CuCI + NH3 + CO [CuCONH3] Cl
Ans 10) a
Ans Desc 10) CO combines with Hb of blood to form carboxyhaemoglobin which reduces the oxygen carrying capacity of Hb. Hb + CO Carboxy haemoglobin.
Ans 11) c
Ans Desc 11) Solid C02 is called dry ice since it does not wet the surface on which it rests.
Ans 12) b
Ans Desc 12) SiO2 has a three dimensional network giant covalent structure in which each Si is sp3-hybridized and is surrounded by four oxygen atoms arranged tetrahedrally around it. Each oxygen is further linked to two Si atoms arranged linearly.
Ans 13) d
Ans Desc 13) In Pb(CH3COO)4, Pb is tetravalent and has a strong tendency to be reduced to Pb2 + state due to the inert pair effect. Thus Pb(CH3COO)4 acts as a strong oxidising agent.
Ans 14) d
Ans Desc 14) Sn + 2 NaOH + H20 Na2Sn03 + 2 H2
Ans 15) a
Ans Desc 15)
Sn + 4HNO3 H2,SnO3 + 4 NO2 + H2O
Metastannic acid or b-stannic acid
Ans 16) a
Ans Desc 16) Dihalides of the carbon family members are ionic in nature whereas tetrahalides are covalent.
Ans 17) d
Ans Desc 17)
Lead reacts with NaOH to form Na2PbO2 and not Pb(OH)4
Pb + 2 NaOHà Na2PbO2+H2
Ans 18) b
Ans Desc 18) SnCl4 is oxidising and not reducing in nature. It is reduced to give more stable Sn2+ species.
Ans 19) c
Ans Desc 19) Sandhur is Pb304 which is a mixture of PbO and PbO2. it is also called red lead.
Ans 20) a
Ans Desc 20) White lead is also called basic lead carbonate. It is formed when Na2CO3 is added to any lead salt solution.
3 Pb(NO3)2 + 3 Na2CO3 + H2OPb(OH)2.2 PbC03 + 6 NaN03 + C02
Ans 21) c
Ans Desc 21) H2S reacts with Pb2 + ions to form PbS which is black in colour.
Pb2++H2S PbS (black) + 2 H+
Ans 22) b
Ans Desc 22) Chrome yellow is PbCrO4.
Ans 23) a
Ans Desc 23) In silicates, (Si04)4- units are present in which each Si atom is sp3-hybridized and is surrounded by four oxygen atoms tetrahedrally.
Ans 24) d
Ans Desc 24) Glass is a homogeneous mixture of different silicates of metal and borates
Ans 25) a
Ans Desc 25) Lead is most readily soluble in CH3COOH in presence of oxygen to give lead acetate (known as sugar of lead)
Pb+2 CH3COOH+ 02 à Pb(CH3COO)2 +H20
Ans 26) c
Ans Desc 26) Water in presence of oxygen reacts with Pb (pipes) to form soluble Pb(OH)2 which gives poisonous Pb2+ ions in solution
Pb + O2 + H2O Pb(OH)2
Ans 27) d
Ans Desc 27) Activated charcoal removes colouring matter from pure substances by adsorption process.
Ans 28) c
Ans Desc 28) Carbon does not show + 1 oxidation state in its compounds.
Ans 29) d
Ans Desc 29) Trisilylamine, N(SiH3)3 has a planar structure where N is sp2-hybridized and there is a p-d overlapping (side wise) due to the filled unhybridized p-orbital of N and empty d-orbitals of Si atoms.
Ans 30) d
Ans Desc 30) Lamp black is used in making all these materials mentioned here. Bone black is used for decolourisation of sugar whereas carbon black is used in making tyres.
Ans 31) c
Ans Desc 31) Carbon is most electronegative in its family
Ans 32) a
Ans Desc 32) The percentage of C in anthracite, lignite, bituminous and peat is about 98%, 70%, 55% and 45% respectively.
Ans 33) a
Ans Desc 33) Lead pencil contains graphite and not Pb
Ans 34) d
Ans Desc 34) CCI4, known under the name pyrene is incombustible and is used as a fire extinguisher
Ans 35) d
Ans Desc 35) CO contains C-O triple bond, CO2 contains C-O double bond and contains C-O single bond. Therefore, C—O bond length increases in the order CO < CO2 < CO.
Ans 36) c
Ans Desc 36) Gaseous SnCI2 is angular with sp2 hybridization, the bond angle being 119Â° due to the presence of one lone pair of electrons on Sn.
Ans 37) c
Ans Desc 37) Pb due to the inert pair effect shows the most stable + 2 oxidation state
Ans 38) c
Ans Desc 38) SnO2 is amphoteric. It dissolves in acids as well as in alkalies. For example,
SnO2 + 4 HCl SnCI4 + 2 H2O;
SnO2+2NaOHNa2SnO3 + H2O
Ans 39) b
Ans Desc 39) Pb4 + is a strong oxidising agent and oxidises l– and Br– to I2 and Br2 and thus gives Pbl2 and PbBr2.
PbBr4 PbBr2 + Br2;
Pbl4Pbl2 + l2
Ans 40) b
Ans Desc 40) Graphite is the most stable allotrope of carbon at high temperatures.
Ans 41) b
Ans Desc 41) In fullerene (C60), the type of hybridization involved is sp2.
Ans 42) a
Ans Desc 42) The extent of hydrolysis increases in the order: CCI4 < MgCI2 < AICI3 < SiCI4 < PCI5
Ans 43) c
Ans Desc 43) Si -F bond dissociation energy is highest.
|Bond energy kJmol-1||540||215||165||152|
Ans 44) c
Ans Desc 44) A mixture of sand (SiO2) and baking soda (NaHC03) is used as a dry powder fire extinguisher.
Ans 45) a
Ans Desc 45) Solid CO2, dry ice is also called drikold.
Ans 46) b
Ans Desc 46) Charcoal dissolves slowly in hot dil. HN03 forming a brown substance called artificial tannin. However, conc. HNO3 oxidises it to CO2 and itself is reduced to N02 and H2O
C + 4HNO3 CO2 + 4 NO2 + 2 H2O
Ans 47) b
Ans Desc 47) Gun shots contain Pb metal which causes Pb poisoning in the body
Ans 48) d
Ans Desc 48) In the sale of diamonds, the unit of weight is carat which is equal to 200 mg.
Ans 49) c
Ans Desc 49) “Aqua dag” is a suspension of graphite in water and is used as a lubricant.
Ans 50) c
Ans Desc 50) Isostructural means having the same shape. CO2, HgCI2 and C2H2 are all linear whereas SnCI2 and NO2 have bent structures.
Ans 51) d
Ans Desc 51) CO2, HgCI2 and Znl2 are all linear whereas SnCI2 and SCI2 are bent.
Ans 52) d
Ans Desc 52) BeO and Sn02 are amphoteric, C02 is acidic whereas Ag2O is basic in nature.
Ans 53) d
Ans Desc 53) Both graphite and diamond are the pure forms of carbon.
Ans 54) d
Ans Desc 54) Graphite is also a crystalline allotrope of carbon
Ans 55) c
Ans Desc 55) In air, NO reacts at once to form reddish brown NO2. Its reactivity is due to its odd electron.
Ans 56) a
Ans Desc 56) Nitrogen is an essential constituent of all proteins
Ans 57) a
Ans Desc 57) The acidic nature decreases and basic nature increases as we go down the group. Thus Bi forms the most basic oxide and nitrogen forms the least basic oxide.
Ans 58) a
Ans Desc 58) White P is used as rat poison, because it is poisonous. Red P is non-poisonous.
Ans 59) c
Ans Desc 59) H3PO2, H3PO3, H3PO4 and H4P2O7 are monobasic, dibasic, tribasic and tetrabasic respectively.
Ans 60) d
Ans Desc 60) Red P has a polymeric structure consisting of a large number of P atoms.
Ans 61) c
Ans Desc 61) Calcium amm. nitrate (CAN), urea and calcium cyanamide are nitrogenous fertilizers.
Ans 62) b
Ans Desc 62) NH4NO2 2H2O + N2.
Ans 63) c
Ans Desc 63) P4O6 + 6H2O 4H3PO3(Phosphorous acid)
Ans 64) a
Ans Desc 64) The heat of formation of an explosive compound is positive.
Ans 65) a
Ans Desc 65) N2O5 is the most acidic because acidity decreases on moving down the group.
Ans 66) b
Ans Desc 66) PCl5 is trigonal bipyramidal due to sp3d hybridisation. In the formation of PCl5, 5 half filled p-orbitals of 5 chlorine atoms overlap with 5 sp3d hybrid orbitals of P.
Ans 67) d
Ans Desc 67) P4O10 + 6H2O 4H3PO4(Phosphoric acid)
Ans 68) d
Ans Desc 68) NCl3 and NBr3 are not stable.
Ans 69) a
Ans Desc 69) Bi2O3 is basic, As2O3 is amphoteric and P2O3 as well as N2O3 are acidic.
Ans 70) d
Ans Desc 70)
Ans 71) c
Ans Desc 71) 2P2O3 + 6H2O 4H3PO3.
Ans 72) a
Ans Desc 72) Both red P and white P react with chlorine but red P is less reactive.
Ans 73) a
Ans Desc 73) PH4I + NaOH PH3 + NaI + H2O.
Ans 74) b
Ans Desc 74)
Ans 75) a
Ans Desc 75) The N-H bond in NH3 is covalent.
Ans 76) c
Ans Desc 76) Red P has a polymeric structure consisting of a large number of phosphorus atoms
Ans 77) c
Ans Desc 77) P-P bond has less bond dissociation energy than the
Ans 78) a
Ans Desc 78) 3Cu + 8HNO3 (dilute) 3Cu (NO3)2 + 2NO + 4H2O.
Ans 79) d
Ans Desc 79)
Ans 80) c
Ans Desc 80) Nitride in (N3-) is similar in structure to phosphide ion (P3-), because they can accept three electrons to form N3- and P3- ions and achieve a noble gas configuration.
Ans 81) c
Ans Desc 81)
MnO2 + 4HCl MnCl2 + 2H2O + Cl2
2KMnO4 + 16 HCl 2KCl + 2MnCl2+ 8H2O + 5Cl2.
Ans 82) a
Ans Desc 82) The acidity of the acid increases as the electro-negativity of the halogen increases.
Ans 83) d
Ans Desc 83) All can form interhalogen compounds.
Ans 84) a
Ans Desc 84) An increase in acid strength indicates a decrease in the basic strength of the conjugate base. Thus for HOCl < HClO2 < HClO3 < HClO4 the base strength of anion follows the order OCl– >ClO –2 > ClO–3 > ClO –4. The addition of an oxygen atom provides a large volume so that the charge of the anion is easily accommodated. A large uni-negative ion attracts and holds a proton less strongly than a small uni-negative ion.
Ans 85) c
Ans Desc 85) Iodine forms a blue color with starch solution.
Ans 86) a
Ans Desc 86) Fluorine (a halogen) is more reactive than an interhalogen compound.
Ans 87) a
Ans Desc 87) The bond angle in the Cl2 molecule is 180Â°.
Ans 88) b
Ans Desc 88) Chlorine reacts with cold and dilute NaOH in the following way. 2NaOH + Cl2 NaCl +NaCIO + H2O. So the minimum number of moles of NaOH which would be needed to react with Cl2 is 2.
Ans 89) d
Ans Desc 89) Fluorine being very reactive combines with hydrogen even in the dark with an explosion at room temperature.
Ans 90) a
Ans Desc 90) Fluorine is the most electronegative element in the periodic tables. So no reagent can remove electrons from the F– ion.
Ans 91) b
Ans Desc 91) a salt containing the Cl– ion will give a positive chromyl chloride test.
Ans 92) a
Ans Desc 92) No oxyacid is formed by fluorine because it is more electronegative than oxygen. Recent studies, however, show that fluorine also forms an oxyacid HFO. But it is not universally accepted.
Ans 93) a
Ans Desc 93) NaCIO is a salt of NaOH and HClO. Since HOCl is the weakest oxyacid, the solution of NaCIO will be more basic.
Ans 94) a
Ans Desc 94) HCl molecule is formed due to overlapping of the s-orbital of hydrogen and the p-orbital of chlorine.
Ans 95) b
Ans Desc 95) The outer configuration of halogen atom is ns2 np5. After gaining one electron, the configuration of halide ion becomes ns2np6(stable noble gas configuration).
Ans 96) b
Ans Desc 96) 2CaO + 2Cl2 CaCl2 + Ca(ClO)2
Ans 97) b
Ans Desc 97) Cl2 + 6KOH (hot and conc.) 5KCl +KClO3 + 3H2O. KClO3 is used in fire works and safety matches.
Ans 98) b
Ans Desc 98) Br(Z = 35) has the configuration Is22s22p63s23p63d104s24ps. Total no. of p-electrons =6 + 6 + 5 = 17
Ans 99) b
Ans Desc 99) Chlorine is used in the manufacture of insecticides.
Ans 100) a
Ans Desc 100) The increasing order of bond dissociation energy is F-F<H-H<O = O<NO.