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P-Block - Class 12 MCQ


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40 Questions MCQ Test - P-Block

P-Block for Class 12 2024 is part of Class 12 preparation. The P-Block questions and answers have been prepared according to the Class 12 exam syllabus.The P-Block MCQs are made for Class 12 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for P-Block below.
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P-Block - Question 1

Borax on heating with cobalt oxide forms a blue bead of :    

Detailed Solution for P-Block - Question 1

Na2B4O7 → 2NaBO2 + B2O3
B2O3 + Co → CoO + B2O3 or Co(BO2)2
(Blue bead)

P-Block - Question 2

On adding ammonium hydroxide solution to AI2(SO4)3 (aq):    

Detailed Solution for P-Block - Question 2

Al2(SO4)3 + 6NH4OH → 2AI (OH)3 + 3(NH4)2 SO4
AI(OH)3 is insoluble in NH4OH
but soluble in NaOH

P-Block - Question 3

Aluminium becomes passive in nitric acid because it:    

Detailed Solution for P-Block - Question 3

Surface of AI forms AI2O3 in nitric acid and becomes passive.

P-Block - Question 4

AI and Ga have the same covalent radii because of :    

Detailed Solution for P-Block - Question 4

It is a reason for given fact.

P-Block - Question 5

Corundum is:    

Detailed Solution for P-Block - Question 5

It is a fact

P-Block - Question 6

Aqueous solution of potash alum is:    

Detailed Solution for P-Block - Question 6

Due to hydrolysis of AI3+ ions

P-Block - Question 7

Hybridisation of boron in diborane is :    

Detailed Solution for P-Block - Question 7

sp3-hybridisation, but four bonds are neither linear nor in one plane.

P-Block - Question 8

BCI3 does not exist as dimer but BH3 exist as dimer (B2H6) because:    

P-Block - Question 9

Aluminum is more reactive than iron, but aluminium is less easily corroded than iron because:    

Detailed Solution for P-Block - Question 9

The formation of oxide film on AI surface prevents it from further corrosion.

P-Block - Question 10

The cryolite is:    

Detailed Solution for P-Block - Question 10

Crysolite (Na3AIF6) is added to AI2O3 before electrolysis tp lower the fusion temperature of bauxite in order to dissolve it and making good conductor of current.

P-Block - Question 11

Which of the following is pseudoalum?

Detailed Solution for P-Block - Question 11

General formula of alum is 
M2SO4.M2(SO4)3.24H2O

P-Block - Question 12

Nickeloy is an alloy containing.    

Detailed Solution for P-Block - Question 12

The alloy of Ni+AI+Cu is called nickeloy.

P-Block - Question 13

Aqueous ammonia is used as a precipitating reagent for AI3+ ions as AI(OH)3 rather than aqueous NaOH, because:    

Detailed Solution for P-Block - Question 13

 AlCl3 + 3NaOH → Al(OH)3 + 3NaCl
Al(OH)+ OH- → Al(OH)-(soluble)

P-Block - Question 14

Borazole is obtained by reaction of :    

Detailed Solution for P-Block - Question 14

P-Block - Question 15

B-F bond order in BF3 is:    

Detailed Solution for P-Block - Question 15

Due to back bonding (pπ-pπ) giving resonance, bond order in BF3 is 1.33

P-Block - Question 16

Boric acid on heating at 1500C gives:    

Detailed Solution for P-Block - Question 16

P-Block - Question 17

In AI2CI6, which statement is incorrect?    

Detailed Solution for P-Block - Question 17

AI2CI6 has the structure given below:

Bond distance between Al—CI bond forming bridge is 2-21 Aº whereas all other AI—CI bonds have bond lengths 2-06 A.
Angles Cl—Al-—-Cl are 110° and 93° and Al—CI—Al bond is 87°

P-Block - Question 18

The stability of +1 oxidation state among AI,Ga,In and TI increases in the sequence:    

Detailed Solution for P-Block - Question 18

This is +1 oxidation state stability order due to inert pair effect.

P-Block - Question 19

Boric acid is an acid because its molecule:
H3BO3 is monobasic Lewis acid and accept OH- from H2O forming one proton or H+.

Detailed Solution for P-Block - Question 19

H3BO3+H2O → B(OH)-4 + H+

P-Block - Question 20

Which of the following has the minimum heat of dissociation?

Detailed Solution for P-Block - Question 20

The tendency of trimethyl boron to act as Lewis acid decreases due to +I effect of CH3 gp. and thus, coordination becomes weaker.

P-Block - Question 21

Aluminium chloride exists as dimer,AI2CI6 in soild state as well as in solution of non-polar solvent such as benzene. When dissolved in water it gives:

Detailed Solution for P-Block - Question 21

AICI3 is hydrated in water and behaves as ionic compound

P-Block - Question 22

The state of hybridisation of boron and oxygen atoms in boric acid (H3BO3) are respectively:    

Detailed Solution for P-Block - Question 22

In H3BO3, B is sp2-hybridized and oxygen is sp3-hybridized having two lone pair on it. 

P-Block - Question 23

Graphite is good conductor of current but diamond is non-conductor because:    

Detailed Solution for P-Block - Question 23

It is the reason for given fact

P-Block - Question 24

Carbon dioxide is a gas but silica is a solid because:    

Detailed Solution for P-Block - Question 24

It is the reason for given fact

P-Block - Question 25

Which is not correct?    

Detailed Solution for P-Block - Question 25

Ge possesses more tedency to show +4 oxidation state.

P-Block - Question 26

Aluminium carbide reacts with dil. HCI to give:    

Detailed Solution for P-Block - Question 26


P-Block - Question 27

Mg2C3 has the following characteristics:    

Detailed Solution for P-Block - Question 27

P-Block - Question 28

White lead or basic lead carbonate is:    

Detailed Solution for P-Block - Question 28

It is a fact; also known as white lead.

P-Block - Question 29

R3SiCI on hydrolysis forms:    

Detailed Solution for P-Block - Question 29

P-Block - Question 30

Pyrosilicate ion is:

Detailed Solution for P-Block - Question 30

it is a fact

P-Block - Question 31

Activation of charcoal:    

Detailed Solution for P-Block - Question 31

Activated charcoal possesses more adsorption power.

P-Block - Question 32

Tin (IV) chloride (anhydrous) can be obtained:    

Detailed Solution for P-Block - Question 32

P-Block - Question 33

Which of the following is amphoteric?    

Detailed Solution for P-Block - Question 33

CO2, SiO2 and GeO2 are acidic oxides.

P-Block - Question 34

When chloride is passed through molten tin, the product obtained is:    

Detailed Solution for P-Block - Question 34

P-Block - Question 35

Which of the following anion is present in chain structure of silicate?

Detailed Solution for P-Block - Question 35

Anions in chain silicate is or [SiO2-3]or [Si4O6-11]n

P-Block - Question 36

Which of these is not a monomer for a high molecular mass silicone polymer?    

Detailed Solution for P-Block - Question 36

 It forms only dimer.

P-Block - Question 37

Which acid is formed when SiF4 reacts with water?

Detailed Solution for P-Block - Question 37

P-Block - Question 38

Pb and Sn are extracted from their chief ores by:    

Detailed Solution for P-Block - Question 38


P-Block - Question 39

The thermal stability order for group 14 halides is:    

Detailed Solution for P-Block - Question 39

The stability of group 14 tetrahalides decreases down the group where as of dihalides increases down the group.

P-Block - Question 40

Under hydrolytic conditions, the compounds used for preparation of linear polymer and for chain termination, respectively, are:    

Detailed Solution for P-Block - Question 40




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