Q.1 Which of the following is the most stable oxidation state of boron?
+1
+2
+3
+4
Explanation - Boron, being electron-deficient, commonly exhibits the +3 oxidation state in its compounds.
Correct answer is: +3
Q.2 Which group 13 element forms an oxide that is amphoteric in nature?
Boron
Aluminium
Gallium
Indium
Explanation - Aluminium oxide reacts with both acids and bases, displaying amphoteric behavior.
Correct answer is: Aluminium
Q.3 Which of the following hydrides of boron is used as a rocket fuel?
B2H6
BH3
B4H10
B5H9
Explanation - Diborane (B2H6) is highly combustible and is used in rocket propulsion.
Correct answer is: B2H6
Q.4 Which of the following is a characteristic property of group 14 elements?
Only metallic nature
Tendency to form covalent compounds
Only non-metallic nature
Tendency to form ionic compounds
Explanation - Group 14 elements (C, Si, Ge, Sn, Pb) generally form covalent compounds due to moderate electronegativity.
Correct answer is: Tendency to form covalent compounds
Q.5 Which allotrope of carbon has a tetrahedral structure?
Graphite
Diamond
Fullerene
Amorphous carbon
Explanation - Diamond consists of carbon atoms in a tetrahedral network, each bonded to four other carbon atoms.
Correct answer is: Diamond
Q.6 The Lewis acid strength of BX3 (X = halogen) increases in the order:
BF3 < BCl3 < BBr3 < BI3
BF3 > BCl3 > BBr3 > BI3
BF3 = BCl3 = BBr3 = BI3
BBr3 < BI3 < BCl3 < BF3
Explanation - The electron deficiency at boron decreases from BI3 to BF3 due to back bonding, making Lewis acidity increase from BF3 to BI3.
Correct answer is: BF3 < BCl3 < BBr3 < BI3
Q.7 Which of the following oxides of carbon is acidic?
CO
CO2
C3O2
C12O6
Explanation - Carbon dioxide reacts with water to form carbonic acid (H2CO3), displaying acidic behavior.
Correct answer is: CO2
Q.8 Which is the heaviest stable element of group 14?
Tin
Lead
Germanium
Silicon
Explanation - Lead (Pb) is the heaviest stable element in group 14 with atomic number 82.
Correct answer is: Lead
Q.9 Which of the following is used as a semiconductor in electronics?
Carbon
Silicon
Tin
Lead
Explanation - Silicon, a group 14 element, is widely used in semiconductor devices due to its suitable band gap.
Correct answer is: Silicon
Q.10 Which group 13 element forms a toxic hydride with the formula TlH3?
Boron
Aluminium
Gallium
Thallium
Explanation - Thallium forms thallium trihydride (TlH3), which is unstable and highly toxic.
Correct answer is: Thallium
Q.11 Which of the following oxides of group 14 elements is amphoteric?
CO
SiO2
SnO2
PbO2
Explanation - Tin dioxide reacts with both acids and bases, showing amphoteric properties.
Correct answer is: SnO2
Q.12 The most common oxidation state of lead in its compounds is:
+2
+4
+3
+1
Explanation - Due to inert pair effect, lead predominantly shows +2 oxidation state rather than +4.
Correct answer is: +2
Q.13 Which of the following compounds is an example of a boron halide?
BF3
B2O3
BCl2H
B2H6
Explanation - Boron trifluoride (BF3) is a classic example of a boron halide used as a Lewis acid.
Correct answer is: BF3
Q.14 Which element forms a hydride that is a strong reducing agent?
Boron
Aluminium
Gallium
Thallium
Explanation - Aluminium hydride (AlH3) and related aluminium hydrides are strong reducing agents.
Correct answer is: Aluminium
Q.15 Which of the following carbon compounds is used in medical X-ray tubes?
Diamond
Graphite
Fullerene
Carbon black
Explanation - Graphite is used as a target in X-ray tubes due to its high melting point and conductivity.
Correct answer is: Graphite
Q.16 Which oxide of boron is used in making borosilicate glass?
B2O3
BO
B2O5
B3O6
Explanation - Boron trioxide (B2O3) is added to glass to improve thermal and chemical resistance, forming borosilicate glass.
Correct answer is: B2O3
Q.17 Which group 14 element is least likely to form multiple bonds?
Carbon
Silicon
Germanium
Tin
Explanation - Heavier group 14 elements like tin and lead rarely form multiple bonds due to poor p-orbital overlap.
Correct answer is: Tin
Q.18 Which group 13 element is liquid at room temperature?
Boron
Aluminium
Gallium
Thallium
Explanation - Gallium melts at around 29.8°C and can melt in the hand, making it unique among group 13 metals.
Correct answer is: Gallium
Q.19 Which compound is a Lewis base among the following?
BF3
BCl3
NH3
AlCl3
Explanation - Ammonia has a lone pair on nitrogen and can donate electrons, acting as a Lewis base.
Correct answer is: NH3
Q.20 Which group 14 element exhibits the most pronounced inert pair effect?
Carbon
Silicon
Germanium
Lead
Explanation - The inert pair effect increases down the group, making Pb(+2) more stable than Pb(+4).
Correct answer is: Lead
Q.21 Which of the following is a semi-metal (metalloid) of group 14?
Carbon
Silicon
Tin
Lead
Explanation - Silicon shows properties of both metals and non-metals, classifying it as a metalloid.
Correct answer is: Silicon
Q.22 Which of the following is NOT a common property of boron and aluminium?
Form covalent compounds
Low density
Form trihalides
Act as Lewis acids
Explanation - While both form covalent compounds, trihalides, and act as Lewis acids, aluminium is significantly denser than boron.
Correct answer is: Low density
Q.23 Which allotrope of carbon has a structure made of pentagonal and hexagonal rings?
Diamond
Graphite
Fullerene
Amorphous carbon
Explanation - Fullerenes (C60) have molecules made of pentagonal and hexagonal carbon rings forming a spherical structure.
Correct answer is: Fullerene
Q.24 Which of the following compounds is used as an antacid?
Al(OH)3
B2O3
SiO2
PbO
Explanation - Aluminium hydroxide neutralizes stomach acid and is widely used in antacid formulations.
Correct answer is: Al(OH)3