Class 12 Chemistry Chapter 7 p Block Elements MCQs | Class 12 Chemistry Chapter 7 p Block Elements Objective Type Questions and Answers

Questions
1 When Al is added to KOH solution
A No action takes place
B Oxygen is evolved
C Water is produced
D Hydrogen is evolved

Answer:Hydrogen is evolved
2 Aluminium is more reactive than iron. But Aluminium is less easily corroded than iron because
A Aluminium is noble metal
B Oxygen forms a protective oxide layer
C Iron forms mono and divalent ions
D All the given

Answer:Oxygen forms a protective oxide layer
3 Aluminium vessels should not be washed with materials containing washing soda since
A Washing soda is expensive
B Washing soda is easily decomposed
C Washing soda reacts with aluminium to form soluble aluminate
D Washing soda reats with aluminium to form insoluble aluminium oxide

Answer: Washing soda reacts with aluminium to form soluble aluminate
4 Which of the statements about anhydrous aluminium chloride is corret
A It exists as AlCl3 molecule
B It is not easily hydrolysed
C It sublimes at 100°C under vaccum
D All the given

Answer:It sublimes at 100°C under vaccum
5 Number of water molecules in Mohr’s salt is
A 7
B 6
C 5
D 8

Answer: 6
6 The liquid field metal expanding on solidification is
A Ga
B Al
C Zn
D Ca

Answer:Ga
7 Aluminium chloride exists as dimer, Al2Cl6 in solid state as well as in solution of non-polar solvents such as benzene when dissolved in water gives
A [Al(OH)6)3- + 3HCl
B [Al(H2O)6)3- + 3Cl-
C Al3+ + 3Cl-
D Al2O3+6HCl

Answer:[Al(H2O)6)3- + 3Cl-
8 The hardest substance amongst the following is
A Be2C
B Graphite
C SiC
D Titanium

Answer:Titanium
9 Inorganic Benzene is
A B2H6
B B3N3H6
C B3O3H6
D (BH3)3

Answer: B3N3H6
10 Anhydrous AlCl3 cannot be obtained from which of the following reactions
A Heating AlCl3 • 6H2O
B By Passing dry HCl over hot aluminium powder
C By Passing dry Cl2 over hot aluminium powder
D By passing dry Cl2 over a hot mixture of alumina and coke

Answer: Heating AlCl3 • 6H2O
11 Diborane combines with ammonia at 120°C to give
A B2H6 NH3
B B2H6. 2NH3
C B2H6.3NH3
D B2H6.4 NH3

Answer: B2H6. 2NH3
12 Which metal burn in air at high temperature with the evolution of much heat.
A Cu
B Hg
C Pb
D Al

Answer: Al
13 Moissan boron is ________
A Amorphous boron of ultra purity
B Crystaline boron of ultra purity
C Amorphous boron of low purity
D Crystalline boron of low purity

Answer: Amorphous boron of low purity
14 Which of the following is only acidic in nature
A Be(OH)2
B Mg(OH)2
C B(OH)3
D Al(OH)3

Answer:B(OH)3
15 Which of the following does not exist in free form

(a) (b) (c) (d)

A BF3
B BCl3
C BBr3
D BH3

Answer:BH3
16 Alumina is ________
A Acidic
B Basic
C Amphoteric
D None of these

Answer: Amphoteric
17 Hydrogen gas will not produce
A Heated cupric oxide
B Heated ferric oxide
C Heated stannic oxide
D Heated aluminium oxide

Answer:Heated aluminium oxide
18 Conc.HNO3 ________
A Reacts with aluminium vigrously
B Reacts with aluminium to form aluminium nitrate
C Doesn’t react with aluminium
D Reacts with platinum

Answer: Doesn’t react with aluminium
19 Anhydrous AlCl3 is obtained from
A Dilute HCl & aluminium metal
B Aluminium & chlorine gas
C Hydrogen chloride gas & aluminium metal
D None of the above

Answer: Hydrogen chloride gas & aluminium metal
20 Which is true for an element & present in III group of the periodic table
A It is gas at room temperature
B It has oxidation state of +4
C It forms R2O3
D It forms RX2

Answer: It forms R2O3

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