Topic: Group 13 — B, Al, Ga, In, Tl
Level: JEE Main + NEET | PYQ-pattern
Type: Single correct answer
Questions
1. The element of Group 13 having the highest first ionisation enthalpy is:
A. B
B. Al
C. Ga
D. Tl
2. Which of the following is the most stable oxidation state of thallium?
A. +3
B. +2
C. +1
D. +5
3. The correct order of atomic radii of Group 13 elements is:
A. B < Al < Ga < In < Tl
B. B < Ga < Al < In < Tl
C. Tl < In < Ga < Al < B
D. B < Al < In < Ga < Tl
4. The anomalous behaviour of boron among Group 13 elements is mainly due to:
A. Large size and low ionisation enthalpy
B. Small size, high ionisation enthalpy and absence of d-orbitals
C. Presence of vacant d-orbitals
D. Metallic nature
5. Which Group 13 element is a metalloid?
A. B
B. Al
C. In
D. Tl
6. Boron does not form B3+ ion readily because:
A. Boron has low ionisation enthalpy
B. Boron has a very large atomic size
C. Removal of three electrons requires very high energy
D. Boron has three lone pairs
7. Which of the following compounds is electron deficient?
A. NH3
B. CH4
C. BF3
D. H2O
8. The hybridisation of boron in BF3 is:
A. sp
B. sp2
C. sp3
D. dsp2
9. BF3 acts as a Lewis acid because:
A. It contains a lone pair on boron
B. Boron has an incomplete octet
C. Fluorine donates electrons permanently
D. It contains a positive charge
10. Which of the following is the strongest Lewis acid?
A. BF3
B. BCl3
C. BBr3
D. BI3
11. The Lewis acidity order of boron trihalides is:
A. BF3>BCl3>BBr3>BI3
B. BF3<BCl3<BBr3<BI3
C. BI3<BBr3<BCl3<BF3
D. BCl3<BF3<BI3<BBr3
12. The comparatively low Lewis acidity of BF3 is due to:
A. Hydrogen bonding
B. Strong pπ−pπ back bonding
C. Ionic character
D. Steric hindrance
13. Borax has the formula:
A. Na2B4O7
B. Na2B4O7⋅10H2O
C. NaBO2
D. NaBH4
14. Orthoboric acid is:
A. Monobasic
B. Dibasic
C. Tribasic
D. Tetrabasic
15. Boric acid behaves as a Lewis acid because:
A. It donates H+ directly
B. It accepts OH− from water
C. It releases H−
D. It contains a B–B bond
16. The correct formula of orthoboric acid is:
A. HBO2
B. H2B4O7
C. H3BO3
D. HBO3
17. When boric acid is heated strongly, the final product formed is:
A. B2O3
B. BO2
C. B2H6
D. B4C
18. Which of the following is used in the preparation of boric acid?
A. Borax + HCl
B. B2O3+NaOH
C. BF3+H2
D. AlCl3+H2O
19. Diborane (B2H6) contains:
A. Only normal 2-centre–2-electron bonds
B. Only 3-centre–2-electron bonds
C. Four B–H terminal bonds and two bridging B–H–B bonds
D. Six bridging hydrogen atoms
20. The number of 3-centre–2-electron bonds in diborane is:
A. 1
B. 2
C. 3
D. 4
21. Which of the following is used as a reducing agent?
A. BF3
B. B2H6
C. B2O3
D. H3BO3
22. Aluminium chloride exists as a dimer Al2Cl6 in the vapour phase at lower temperature. The dimer contains:
A. 2 coordinate bonds
B. 4 coordinate bonds
C. 6 coordinate bonds
D. No coordinate bonds
23. Aluminium chloride is electron deficient because aluminium in AlCl3 has:
A. 2 electrons around it
B. 4 electrons around it
C. 6 electrons around it
D. 8 electrons around it
24. Which of the following oxides is amphoteric?
A. B2O3
B. Al2O3
C. Tl2O3
D. B2O3 and Al2O3
25. The acidic character of Group 13 oxides generally:
A. Increases down the group
B. Decreases down the group
C. Remains constant
D. First decreases then becomes zero
26. Which of the following compounds is formed when aluminium reacts with NaOH and water?
A. AlCl3
B. Na[Al(OH)4]
C. Al2O3
D. NaAlO2 only, under all conditions
27. The correct order of stability of oxidation states for thallium is:
A. Tl3+>Tl+
B. Tl+>Tl3+
C. Tl2+>Tl+
D. Tl5+>Tl3+
28. The inert pair effect in Group 13 is maximum for:
A. B
B. Al
C. In
D. Tl
29. Which of the following statements about boron is incorrect?
A. It is a metalloid.
B. It does not form B3+ ion easily.
C. It forms electron-deficient compounds.
D. It readily forms B3+ in aqueous solution.
30. Which one of the following pairs is incorrectly matched?
A. B2O3 — Acidic oxide
B. Al2O3 — Amphoteric oxide
C. Tl2O3 — Basic oxide
D. BF3 — Lewis base
Answer Key
| Q | Ans | Q | Ans | Q | Ans |
|---|---|---|---|---|---|
| 1 | A | 11 | B | 21 | B |
| 2 | C | 12 | B | 22 | B |
| 3 | B | 13 | B | 23 | C |
| 4 | B | 14 | A | 24 | B |
| 5 | A | 15 | B | 25 | B |
| 6 | C | 16 | C | 26 | B |
| 7 | C | 17 | A | 27 | B |
| 8 | B | 18 | A | 28 | D |
| 9 | B | 19 | C | 29 | D |
| 10 | D | 20 | B | 30 | D |
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