Uses of Boron and Aluminium - Class 11 Chemistry MCQ

This set of Class 11 Chemistry Chapter 11 Multiple Choice Questions & Answers (MCQs) focuses on “p-Block Elements – Uses of Boron and Aluminium and their Compounds”.

1. What is ammonal?
a) a mixture of aluminium powder with ammonium nitrite
b) a mixture of aluminium powder with ammonium nitrate
c) a mixture of aluminium powder with ammonium sulphate
d) a mixture of aluminium powder with ammonium chloride
View Answer

Answer: b
Explanation: A mixture of aluminium powder with ammonium nitrate is called ammonal and is used in bombs with a ratio of 5:95. Here the aluminium acts as a fuel and ammonium nitrate as an oxidizer, it was first used in the year 1916 by the britishers near mines.

2. Which of the following material is used for making fireproof clothes?
a) Aluminium chloride
b) Aluminium oxide
c) Aluminium nitrate
d) Aluminium sulphate
View Answer

Answer: d
Explanation: Aluminium sulphate which is given by the chemical formula Al₂(SO₄)₃ is used for making fireproof clothes and it is also used as a fire fighting foam. Aluminium sulphate is also used as an antiseptic, astringent and also as a modern in dyeing textiles.

3. Which of the following is not a use of Boron?
a) silver paints
b) bulletproof vest
c) in nuclear reactors
d) making of boron fibres
View Answer

Answer: a
Explanation: There are many applications of boron like heat resistant glasses, glass wool, fibreglass, flux for soldering metals, for heat, scratch and stain resistant glazed coating to earth and wears and as a constituent of medical soaps. It is also used and the making of Boron fibres, bulletproof vest making and also and nuclear reactions in order to absorb neutrons.

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4. Boron is used as a ______________
a) double insulator
b) semiconductor
c) insulator
d) conductor
View Answer

Answer: b
Explanation: Yes, Boron is used as a semiconductor and also Boron Steel rods are used for controlling the nuclear reactions. Boron is used as a dopant for semiconductors such as Silicon and Germanium. Pure Boron is a black, lustrous semiconductor.

5. Which of the following is not a use of orthoboric acid?
a) painting
b) antiseptic
c) eye lotion
d) food preservative
View Answer

Answer: a
Explanation: Orthoboric acid which is given by the chemical formula H3BO₃ is used as an antiseptic and eye lotion under the name boric lotion and it is also used as a food preservative. The boric lotion is a saturated solution of 4% boric acid in water.

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6. Which of the following is used as a catalyst in Friedel craft reaction?
a) cement
b) boron
c) anhydrous aluminium chloride
d) borax
View Answer

Answer: c
Explanation: Friedel crafts reactions are the reactions in which substituents are added to the aromatic rings. There are two types of friedel craft reactions namely alkylation and acylation. Anhydrous aluminium chloride is used as a catalyst in these Friedel craft reactions.

7. What is the chemical formula of alumina and anhydrous aluminium chloride?
a) Al₂O₃, AlCl
b) Al₂O₃, AlCl₃
c) Al₂O, AlCl₃
d) AlO₃, AlCl₃
View Answer

Answer: b
Explanation: The chemical formula of alumina is Al₂O₃ and that of anhydrous aluminium chloride is AlCl₃. Alumina is nothing but aluminium oxide. Anhydrous aluminium chloride is prepared by heating a mixture of alumina and carbon in a current of dry chlorine.

8. Aluminium oxide as otherwise called as ______________
a) aluminium sulphate
b) alumina
c) alum
d) aluminium
View Answer

Answer: b
Explanation: Alumina is also known as aluminium oxide and it is the most stable compound of aluminium that occurs in nature as colourless corundum and several coloured oxides, like ruby, topaz, sapphire, and emerald, these are used as precious stones.

9. Alum is a double sulphate.
a) true
b) false
View Answer

Answer: a
Explanation: The term alum is given to double sulphates of the type X₂SO₄.Y₂(SO₄)₃.24H₂O where, X represents a monovalent cation such as sodium ion, potassium ion and ammonium while why is a trivalent cation such as aluminium 3 +, chromium 3 +, ferrous 3 + and Cobalt 3 +. Lithium-ion does not form alum.

10. Which of the following is not an alum?
a) covalent alum
b) Potash alum
c) ammonium alum
d) sodium alum
View Answer

Answer: a
Explanation: K₂SO₄.Al₂(SO₄)₃.24H₂O, Na₂SO₄.Al₂(SO₄)₃.24H₂O, (NH₄)₂SO₄.Al₂(SO₄)₃.24H₂O and (NH₄)₂SO₄.Fe₂(SO₄)₃.24H₂O are respective chemical formulae of Potash alum, sodium alum, ammonium alum and ferric alum.

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