This set of BPSC PGT Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “p-Block Elements – Uses of Boron and Aluminium and Their Compounds.”
- Which of the following material is used for making fireproof clothes?
a) Aluminium chloride
b) Aluminium oxide
c) Aluminium nitrate
d) Aluminium sulphate
Answer: d
Explanation: Aluminum sulphate (Al₂(SO₄)₃) is used to make fireproof clothing and as a firefighting foam. It also serves as an antiseptic, astringent, and mordant in textile dyeing.
- 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
Answer: b
Explanation: A mixture of aluminum powder and ammonium nitrate, known as ammonal, is used in explosives with a 5:95 ratio. In this mixture, aluminum serves as the fuel, while ammonium nitrate acts as the oxidizer. It was first used by the British near mines in 1916.
- Boron is used as a ______________
a) double insulator
b) semiconductor
c) insulator
d) conductor
Answer: b
Explanation: Boron is used as a semiconductor and in boron steel rods for controlling nuclear reactions. It serves as a dopant for semiconductors like silicon and germanium. Pure boron is a black, lustrous semiconductor.
- 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
Answer: a
Explanation: Boron has various applications, including heat-resistant glass, glass wool, fiberglass, and flux for soldering metals. It is also used for heat, scratch, and stain-resistant glazed coatings on ceramics, as a component in medical soaps, and in the production of boron fibers and bulletproof vests. Additionally, boron plays a role in nuclear reactions by absorbing neutrons.
- Which of the following is used as a catalyst in Friedel craft reaction?
a) cement
b) boron
c) anhydrous aluminium chloride
d) borax
Answer: c
Explanation: Friedel-Crafts reactions involve the addition of substituents to aromatic rings and are classified into two types: alkylation and acylation. Anhydrous aluminum chloride serves as a catalyst in these reactions.
- Which of the following is not a use of orthoboric acid?
a) painting
b) antiseptic
c) eye lotion
d) food preservative
Answer: a
Explanation: Orthoboric acid (H₃BO₃) is used as an antiseptic and eye lotion, commonly known as boric lotion. It is also used as a food preservative. Boric lotion is a 4% saturated solution of boric acid in water.
- What is the chemical formula of alumina and anhydrous aluminum chloride?
a) Al2O3, AlCl
b) Al2O3, AlCl3
c) Al2O, AlCl3
d) AlO3, AlCl3
Answer: b
Explanation: Alumina, also known as aluminum oxide, has the chemical formula Al₂O₃, while anhydrous aluminum chloride is represented as AlCl₃. Anhydrous aluminum chloride is produced by heating a mixture of alumina and carbon in a stream of dry chlorine.
- Alum is a double sulfate.
a) true
b) false
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.
- Which of the following is not an alum?
a) covalent alum
b) Potash alum
c) ammonium alum
d) sodium alum
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.
- Aluminium oxide as otherwise called as ______________
a) aluminium sulphate
b) alumina
c) alum
d) aluminium
Answer: b
Explanation: Alumina, also known as aluminum oxide, is the most stable compound of aluminum. It naturally occurs as colorless corundum and in various colored forms such as ruby, topaz, sapphire, and emerald, which are used as precious gemstones.