Problem 58
Borax is not used (1) as an antiscptic (2) in making cnamels and pottery glazes (3) as a flux in soldering (4) in making optical glasses
Problem 59
Boric acid is prepared from the borax by the action of (1) hydrochloric acid (2) sodium hydroxide (3) carbon dioxide (4) sodium carbonate
Problem 60
Borax when dissolved in water exhibits (1) alkaline nature (2) acidic nature (3) neutral behaviour (4) amphoteric behaviour
Problem 61
Which of the following statements is false about boric acid \(\mathrm{H}_{3} \mathrm{BO}_{3} ?\) (1) It is prepared by acidifying an aqueous solution of borax. (2) It has a layer structure in which planar \(\mathrm{BO}_{3}\) units are joined by hydrogen bonds. (3) It is a strong tribasic acid. (4) It does not act as proton donor but act as a Lewis acid by accepting hydroxide ion.
Problem 62
When boron is four co-ordinatc, the compound conforms a (1) tetrahedral geometry (2) square planar geometry (3) triangular geometry (4) none of these
Problem 64
Identify the false statement. (1) Boric acid behaves as a strong acid in the presence of catechol. (2) Boron forms stable \(\left[\mathrm{BF}_{6}\right]^{3-}\) (3) \(\mathrm{Tl}(\mathrm{OH})_{3}\) is basic. (4) The first ionization potential of \(\mathrm{B}\) and \(\mathrm{Al}\) is lower than that of \(\mathrm{Be}\).
Problem 65
In borax bead test, which component of the bead reacts with basic radical to form metaborate? (1) \(\mathrm{Na}_{2} \mathrm{BO}_{3}\) (2) \(\mathrm{B}_{2} \mathrm{O}_{3}\) (3) \(\mathrm{NaBO}_{2}\) (4) \(\mathrm{Na}_{2} \mathrm{~B}_{4} \mathrm{O}_{7}\)
Problem 67
Which of the following statements is false about boric acid? (1) Boron is in \(s p^{3}\) hybridization. (2) It has layer structure in which planar \(\mathrm{BO}_{3}\) units are linked by hydrogen bonding. (3) It can be used as solid lubricant as the layers are slippery. (4) Different layers are held by weak Van der Waal's forces.
Problem 69
Which of the following statements is falsc? (1) \(\mathrm{B}(\mathrm{OII})_{3}\) partially reacts with water to form \(\mathrm{II}_{3} \mathrm{O}^{+}\) and \(\left[\mathrm{B}(\mathrm{OII})_{4}\right]^{-}\) and behaves like a weak acid. (2) \(\mathrm{B}(\mathrm{OII})_{3}\) behaves like a strong monobasic acid in the presence of sugars and this acid can be titrated against on NaOII solution using phenolphthalein. (3) \(\mathrm{B}(\mathrm{OII})_{3}\) does not donate a proton and hencc does not form any salt of NaOII. (4) \(\mathrm{B}(\mathrm{OII})_{3}\) reacts with \(\mathrm{NaO}\) II forming \(\mathrm{Na}\left[\mathrm{B}(\mathrm{OII})_{4}\right]^{-}\).
Problem 71
Which of the following statements is false? (1) Boron carbide is uscd as abrasive. (2) Boron is used to increasc the hardenability of stecl. (3) Boron scsquioxide \(\mathrm{B}_{2} \mathrm{O}_{3}\) is uscd in the manufacture of borosilicate glass. (4) Orthoboric acid undergoes intramolecular hydrogen bonding.
