P Block Elements: Chemistry Entrance

 

Q.1. Which of the following is a tetrabasic acid ?

A) Orthophosphoric acid

B) Hypo phosphorous acid

C) Metaphosphoric acid

D) Pyrophosphoric acid

Explanation-

Pyrophosphoric acid : 

(Tetrabasic)  

Q.2. When ammonia is passed over heated copper oxide, the metallic copper is obtained, The reaction shows that ammonia is

A) A dehydrating agent

B) An oxidizing agent

C) A reducing agent

D) A nitrating agent

Explanation-

 

Q.3.  Which is the most amphoteric oxide ?

A) NaO

B) MgO

C) AlO

D) CaO

Explanation-

Oxide of aluminum is amphoteric in nature, whereas NaO, MgO and CaO are basic in nature.

Q.4. Which of the following statements is incorrect  ?

A) BF  is the weakest Lewis acid 

B) Ammonal is a mixture of aluminium compounds and is used in bombs 

C) BF exists as dimer 

D) BCI  does not conduct electricity in its molten state 

Explanation-

 BF exists as dimer.

Q.5.  Orthoboric acid contains 

A) Pyramidal   units

B) Linear   units 

C) T-shaped   units 

D) Triangular   units    

Explanation-

Orthoboric acid  contains triangular  units joined together through H-bonding forming a trigonal planar layer structure.

Q.6. Aluminum deposited as vapors on glass forms a good mirror, essentially because 

A) It has better shine than Ag

B) It does not scratch

C) Coating is  much smoother

D) It does not tarnish in air

Explanation-

Aluminum being passive metal does not tarnish in air.

Q.7. In the electrolytic extraction of aluminum fused cryolite is added

A) To make a conduction solution of bauxite

B) To act as reducing agent

C) To increase Al production

D) To protect the anodes

Explanation-

Addition of cryolite to fused alumina during electrolytic extraction make the solution more conducting and low melting.

Q.8.  Which of the metal chlorides has maximum covalent character ?

A) NaCl

B) AlCl

C) CsCl

D) BaCl 

Explanation-

 has minimum size and maximum charges, hence forms compound with maximum covalent character among given choice. The covalent character of chlorides increases along a period and decreases down a group according of Fajan's rule.

Q.9. When concentrated  is heated with , brown fumes evolve. These fumes are due to

A) 

B) 

C) 

D)  

Explanation-

 

Q.10. Which one of the following elements is most metallic ?

A) P

B) As

C) Sb

D) Bi

Explanation-

Metallic character increases down the group.