Boron Carbide (B4C) MCQs
Previous Years Questions (NEET • JEE Main & Advanced • GATE • CSIR-NET • IIT-JAM)
Chemical formula of boron carbide is
- B2C
- B4C
- B12C3
- BC
Answer
Boron carbide is prepared by
- B2O3 + 7C → B4C + 6CO
- B + C → BC
- BCl3 + CH4 → B4C
- Mg + B2O3 → B4C
Answer
Mohs hardness of B4C is
- 9.0
- 9.3
- 9.5–9.7
- 10
Answer
B4C is used in nuclear reactors as
- Moderator
- Neutron absorber/control rod
- Fuel pellet
- Reflector
Answer
Lightest ceramic armour material is
- Al2O3
- SiC
- B₄C
- TiB2
Answer
Commercial name of boron carbide is
- Carborundum
- Norbiide
- Moissanite
- Alundum
Answer
Structure of B4C consists of
- B12 icosahedra linked by C–B–C chains
- Graphite-like layers
- Diamond-like network
- Linear polymeric chains
Answer
B4C is extremely hard due to
- Strong covalent bonds & low atomic mass
- Ionic bonding
- Metallic bonding
- Weak van der Waals forces
Answer
Melting point of B4C is approximately
- 2050 °C
- 2450 °C
- 3000 °C
- 3760 °C
Answer
B₄C is used as abrasive for
- Lapping of carbides & gemstones
- Polishing wood
- Cutting plastics
- Soft metals only
Answer
B₄C on hydrolysis at high temperature gives
- Boric acid + methane
- Borax
- Hydrogen only
- No reaction
Answer
Correct order of hardness is
- Diamond > c-BN > B4C > SiC
- B4C > Diamond > c-BN
- SiC > B4C > Diamond
- c-BN > B4C > Diamond
Answer
Boron carbide is used in body armour because it is
- Lightweight & extremely hard
- Heavy & ductile
- Electrically conducting
- Magnetic
Answer
B4C is an electron-deficient compound having
- 3-centre–2-electron bonds
- Normal 2c–2e bonds only
- Ionic bonds
- Metallic bonds
Answer
Colour of pure boron carbide is
- White
- Shiny black
- Green
- Red
Answer
Density of B4C is
- 2.52 g/cm³
- 3.21 g/cm³
- 3.5 g/cm³
- 4.0 g/cm³
Answer
B4C is resistant to
- Cold acids
- Hot conc. HNO3
- Molten iron
- All of these
Answer
Boron carbide is used in sandblasting nozzles because of its
- Extreme hardness & wear resistance
- Softness
- Low cost only
- High electrical conductivity
Answer
The isotope responsible for neutron absorption in B4C is
- ¹¹B
- ¹⁰B
- ¹²C
- ¹³C
Answer
B4C is a
- Covalent carbide
- Ionic carbide
- Interstitial carbide
- Saline carbide
Answer
Boron carbide is used in
- Bulletproof vests
- Glass cutting
- Optical fibres
- Fertilisers
Answer
Which has lowest density among the following?
- SiC
- B4C
- Al2O3
- c-BN
Answer
B4C is used as
- Thermocouple hot junction
- High-temperature thermocouple protection tube
- LED
- Superconductor
Answer
B4C reacts with chlorine at high temperature to form
- BCl3 + C
- BCl3 + CO
- No reaction
- Boron nitride
Answer
Which is NOT a property of B4C?
- Extremely hard
- Very low density
- Good electrical conductor
- High chemical resistance