ranjeet shahi

R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e sS CO 4 8 , I I n d F l o o r , S e c t o r 2 0 C, CHANDI GARH P h : 2 7 2 5 7 4 8 , 3 0 4 0 6 6 0 S C F 7 2 , S e c t o r 1 0 , P a n c h k u l a , P h : 3 9 1 4 8 4 4 1 Copyright © Ranjeet Shahi IIT IIT IIT IIT- -- -JEE JEE JEE JEE Review Questions Boron and its Compounds Level-2(Following Questions may have more than one correct response) Q1. Which of the following statements is/are correct regarding B 2 H 6 ? (A) banana bonds are longer but stronger than normal B–H bonds (B) B 2 H 6 is also known as 3c–2e compound (C) the hybrid state of B in B 2 H 6 is sp 3 while that of sp 2 in BH 3 (D) it cannot be prepared by reacting BF 3 with LiBH 3 in the presence of dry ether A B C Q2. When an inorganic compound (X) having 3e-2e as well as 2e-2e bonds reacts with ammonia gas at a certain temperature, gives a compound (Y) iso-structural with benzene. Compound (X) with ammonia at a high temperature, produces a hard substance (Z). Then (A) (X) is B 2 H 6 (B) (Z) is known as inorganic graphite (C) (Z) having structure similar to graphite (D) (Z) having structure similar to (X) A B C Q3. Boric acid (A) exists in polymeric form due to inter-molecular hydrogen bonding. (B) is used in manufacturing of optical glasses. (C) is a tri-basic acid (D) with borax, it is used in the preparation of a buffer solution. A B D Q4. Select correct statement(s): (A) Borax is used as a buffer (B) 1 M borax solution reacts with equal volumes of 2 M HCl solution (C) Titration of borax can be made using methyl orange as the indicator (D) Coloured bead obtained in borax-bead test contains metaborate A B C D Q5. Select correct statement about B 2 H 6 (A) Bridging groups are electron-deficient with 12 valence electrons (B) It has 2c-2e B–H bonds (C) It has 3c - 2e B–H–B bonds (D) All of above are correct statements B C Q6. Identify the correct statements regarding structure of diborane: (A) there are two bridging hydrogen atoms (B) each boron atom forms four bonds (C) the hydrogen atoms are not in the same plane (D) each boron atom is in sp3 hybridized state A B C D Q7. Which of the following form dimeric halides? (a) Al (b) Mg (c) ln (d) Ga A C D Q8. Which species exist? (a) [BF 6 ] 3- (b) [AlF 6 ] 3- (c) [GaF 6 ] 3- (d) [lnF 3 ] 3- B C D Q9. Borax bead test is given by: (a) An aluminium salt (b) A cobalt salt (c) A copper salt (d) A nickel salt B C D Q10. Identify the statement that is/are correct as far as structure of diborane is concerned: (a) There are two bridging hydrogen atoms in diborane (b) Each boron atom forms four bonds in diborane (c) The hydrogen atoms are not in the same plane in diborane (d) All B-H bonds in diborane are similar. A B C Group-13 R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s S CO 4 8 , I I n d F l o o r , S e c t o r 2 0 C, CHANDI GARH P h : 2 7 2 5 7 4 8 , 3 0 4 0 6 6 0 S C F 7 2 , S e c t o r 1 0 , P a n c h k u l a , P h : 3 9 1 4 8 4 4 2 Copyright © Ranjeet Shahi Q11. Which is/are correct? (a) Al acts as a reducing agent (b) Al does not react with steam even at higher temperature (c) Al forms a number of alloys with other metals (d) Al is ionic in all its compounds. A B C Q12. Aluminium is/are used: (a) In thermite welding (b) As oxidizer in metallurgy (c) For making utensils (d) In silvery paints A C D Q13. Boric acid is used: (a) As an antiseptic (b) As a flux in soldering (c) In making optical glasses (d) In making enamels and pottery glazes A C D Q14. When is/are true in case of BF 3 ? (a) it is volatile liquid even at room temperature (b) It is Lewis acid (c) It has planar geometry (d) It forms adduct with NH 3 B C D Q15. Which of the following is/are correct in case of boron nitride: (a) It is also called borazine (b) It is chemically unreactive (c) It is hard because it has diamond like structure (d) It has magnetic properties. B C Q16. Which of the following statements about anhydrous aluminium chloride is/are incorrect? (a) It exists as AlCl 3 molecule (b) It is a strong Lewis base (c) It sublimes at 100°C under vacuum (d) it is not easily hydrolyzed. A B D Q17. Select the correct statement(s). (a) The graphite diamagnetic and diamond is paramagnetic in nature. (b) Graphite acts as a metallic conductor along the layers of carbon atoms and as semi-conductor perpendicular to the layers of the carbon atoms. (c) Graphite is less denser than diamond (d) C 60 is called as Buckminster fullerene. B C D Assertion Reason Types Questions given below consist of two statements each printed as Assertion (A) and Reason (R); while answering these questions you are required to choose any one of the following four responses: (A) if both (A) and (R) are true and (R) is the correct explanation of (A) (B) if both (A) and (R) are true but (R) is not correct explanation of (A) (C) if (A) is true but (R) is false (D) if (A) is false and (R) is true Q18. Assertion: Borax bead test is applicable only to coloured salt. Reason: In borax bead test, coloured salts are decomposed to give coloured metal meta borates. A Q19. Assertion: Aluminium and zinc metal evolve H 2 gas from NaOH solution Reason: Several non-metals such as P, S, Cl, etc. yield a hydride instead of H 2 gas from NaOH B Q20. Assertion: Al(OH) 3 is amphoteric in nature. Reason: It can not be used as an antacid. C Q21. Assertion: Al(OH) 3 is insoluble in NH 4 OH but soluble in NaOH Reason: NaOH is a stronger base alkali B Q22. Assertion: Boron is metalloid Reason: Boron shows metallic character. C R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s S CO 4 8 , I I n d F l o o r , S e c t o r 2 0 C, CHANDI GARH P h : 2 7 2 5 7 4 8 , 3 0 4 0 6 6 0 S C F 7 2 , S e c t o r 1 0 , P a n c h k u l a , P h : 3 9 1 4 8 4 4 3 Copyright © Ranjeet Shahi Q23. Assertion: Benzene is reactive while inorganic benzene is unreactive compound Reason: ;Inorganic benzene is borazine, B 3 H 3 H 6 D Q24. Assertion: Al forms [AlF 6 ] 3- but B does not form [BF 6 ] 3- Reason: BF 3 on hydrolysis gives HBF 4 B Q25. Assertion: Aluminium (II) does not respond to borax bead test. Reason: Aluminium (III) metaborate is a colourless compound. A Q26. Assertion: AlCl 3 form dimmer Al 2 Cl 6 but it dissolves in H 2 O forming [Al(H 2 O) 6 ] 3+ and Cl - ions. Reason: Aqueous solution of AlCl 3 is acidic due to hydrolysis. B Matching Type Questions Q27. Column-I Column-II (a) Colemanite (i) Na 3 AlF 6 (b) Cryolite (ii) KAl(SO 4 ) 2 . 12H 2 O (c) Bauxite (iii) Ca 2 B 6 O 11 .5H 2 O (d) Potash alum (iv) Na 2 B 4 O 7 .10H 2 O (e) Borax (v) Al 2 O 3 .2H 2 O Q28. Column-I Column-II (a) Inorganic benzene (i) Na 2 B 4 O 7 . 10H 2 O (b) Jeweller’s borax (ii) B 2 H 6 (c) Borax (iii) Na 2 B 4 O 7 .5H 2 O (d) Diborane (iv) Mordant (e) Alum (v) B 3 N 3 H 6 Q29. Column-I Column-II (a) BBr 3 + H 2 → (p) Borax bead test (b) Na 2 B 4 O 7 .10H 2 O + CuSO 4 → (q) Heat (c) AlCl 3 + H 2 O → (r) reduction (d) Cr 2 O 3 + Al → (s) White fumes (t) Hydrolysis R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s R a n j e e t S h a h i C h e m i s t r y C l a s s e s S CO 4 8 , I I n d F l o o r , S e c t o r 2 0 C, CHANDI GARH P h : 2 7 2 5 7 4 8 , 3 0 4 0 6 6 0 S C F 7 2 , S e c t o r 1 0 , P a n c h k u l a , P h : 3 9 1 4 8 4 4 4 Copyright © Ranjeet Shahi Answers 1. A B C 16. A B D 2. A B C 17. B C D 3. A B D 18. A 4. A B C D 19. B 5. B C 20. C 6. A B C D 21. B 7. A C D 22. C 8. B C D 23. D 9. B C D 24. B 10. A B C 25. A 11. A B C 26. 26. 26. 26. B 12. A C D 27. 27. 27. 27. (a= iii, b = i, c = v, d = ii, e = iv) 13. A C D 28. 28. 28. 28. (a = v, b = iii, c = i, d = ii, e = iv) 14. B C D 29. 29. 29. 29. (a = r, b = p, c = t, d = r) 15. B C