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Chapter: 12th Chemistry : p-Block Elements-I

p-Block Elements-I: Choose the correct answer

Chemistry : p-Block Elements-I: Choose the correct answer with Answers, Solution and Explanation

Choose the correct answer:

 

1. An aqueous solution of borax is

a) neutral

b) acidic

c) basic

d) amphoteric

Solution:


 

2. Boric acid is an acid because its molecule

a) contains replaceable H+ ion

b) gives up a proton

c) combines with proton to form water molecule

d) accepts OH- from water ,releasing proton.

Solution:

B(OH)3 + H2O ↔ [B (OH)4 + H+


 

3. Which among the following is not a borane?

a) B2 H6

b) B3 H6

c) B4 H10

d) none of these

Solution:

nido borane : BnH4+n

aracno borane : BnH6+n

B3H6 is not a borane

 

4. Which of the following metals has the largest abundance in the earth’s crust?

a) Aluminium

b) calcium

c) Magnesium

d) sodium

 

5. In diborane, the number of electrons that accounts for banana bonds is

a) six

b) two

c) four

d) three

Solution:

There are two 3c – 2e-bonding in the bridges account for 4 electrons.

 

6. The element that does not show catenation among the following p-block elements is

a) Carbon

b) silicon

c) Lead

d) germanium

 

7. Carbon atoms in fullerene with formula C60 have

a) sp3 hybridised

b) sp hybridised

c) sp2 hybridised

d) partially sp2 and partially sp3 hybridised

 

8. Oxidation state of carbon in its hydrides

a) +4 

b) -4

c) +3

d) +2

Solution:

Example : CH4+ in which the oxidation state of carbon is +4

 

9. The basic structural unit of silicates is

a) ( SiO3 )2

b) ( SiO4 )2

c) ( SiO)

d) ( SiO4 )4

 

10. The repeating unit in silicone is

a) SiO2


Ans: b

 

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

a) Me3SiCl

b) PhSiCl3

c) MeSiCl3

d) Me2SiCl2

 

12. Which of the following is not sp2 hybridised?

a) Graphite

b) graphene

c) Fullerene

d) dry ice

Solution:

dry ice – solid CO2 in which carbon is in sp hybridized state

 

13. The geometry at which carbon atom in diamond are bonded to each other is

a) Tetrahedral

b) hexagonal

c) Octahedral

d) none of these

 

14. Which of the following statements is not correct?

a) Beryl is a cyclic silicate

b) Mg2SiO4 is an orthosilicate

c) SiO4 4is the basic structural unit of silicates

d) Feldspar is not aluminosilicate

 

15. AlF3 is soluble in HF only in the presence of KF. It is due to the formation of

a) K3 [ AlF3H3 ]

b) K3 [ AlF6 ]

c) AlH3

d) K[ AlF3H]

Solution:

AlF3 + 3KF → K3[AlF6]

 

16. Match items in column - I with the items of column – II and assign the correct code.


a) A-2 , B-1 , C-4 , D-3

b) A-1 , B-2 , C-4 , D-3

c) A-1 , B-2 , C-4 , D-3

d) none of these

 

17. Duralumin is an alloy of

a) Cu,Mn

b) Cu,Al,Mg

c) Al,Mn

d) Al,Cu,Mn,Mg

Solution:

Al-95% , Cu-4% , Mn-0.5% , Mn-0.5%

 

18. Thermodynamically the most stable form of carbon is

a) Diamond

b) graphite

c) Fullerene

d) none of these

 

19. The compound that is used in nuclear reactors as protective shields and control rods is

a) Metal borides

b) metal oxides

c) Metal carbonates

d) metal carbide

 

20. The stability of +1 oxidation state increases in the sequence

a) Al < Ga < In < Tl

b) Tl < In < Ga < Al

c) In < Tl < Ga < Al

d) Ga< In < Al < Tl

Solution

stability of +1 oxidation state decreases down the group due to inert pair effect

 

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