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Boron compounds: diborane, boric acid, borax, boron halides

37 questions on Boron compounds: diborane, boric acid, borax, boron halides from the p-Block Elements: Groups 13 and 14 chapter: 8 NEET level, 15 JEE Main, 14 JEE Advanced. Each one opens with its answer and solution.

Practice this topic All p-Block Elements: Groups 13 and 14 topics

The molecular formula of borax (crystalline, as usually written) is NEET level
Orthoboric acid, H3BO3, behaves in water as a NEET level
Diborane, B2H6, contains how many three-centre two-electron (3c-2e) bonds? NEET level
BF3 acts as a Lewis acid because NEET level
A borax bead is heated in the flame with a trace of a cobalt(II) salt. The coloured compound formed in the bead and its colour are JEE Main level
Boric acid cannot be titrated sharply with NaOH using phenolphthalein, but on adding glycerol or mannitol it can be. This is because the polyol JEE Main level
In crystalline orthoboric acid, the planar B(OH)3 units are linked into sheets by JEE Main level
The correct order of Lewis acid strength of boron trihalides is JEE Main level
Hydrolysis of BF3 with water, after the HF formed has reacted with unreacted BF3, finally gives JEE Main level
Select the correct statement(s) about diborane, B2H6. JEE Main level
Select the correct statement(s) about borax. JEE Main level
Diborane hydrolyses completely according to B2H6 + 6H2O -> 2H3BO3 + 6H2. Calculate the volume of hydrogen, in litres at STP, produced from 8.4 g of B2H6. Take B... JEE Main level
The anion of borax is [B4O5(OH)4]^2-. The sum of the number of sp^3 hybridised boron atoms and the number of terminal hydroxyl groups in this anion is JEE Advanced level
On gradual heating, orthoboric acid passes through which sequence of products? JEE Advanced level
Diborane reacts with ammonia on heating to give borazine, B3N3H6 (a planar six-membered ring), with release of hydrogen: 3B2H6 + 6NH3 -> 2B3N3H6 + 12H2. The sum... JEE Advanced level
When BF3 reacts with fluoride ion to form BF4-, the changes in hybridisation of boron, B-F bond length and F-B-F angle are respectively JEE Advanced level
Which statement about boron nitride, (BN)_x, is correct? JEE Advanced level
Select the correct statement(s) about boron trihalides. JEE Advanced level
Select the correct statement(s) about orthoboric acid. JEE Advanced level
How many three-centre two-electron (3c-2e) bonds are present in one molecule of diborane, B2H6? NEET level
Boric acid, H3BO3, in water behaves as NEET level
In the borax bead test, a copper(II) salt heated in the oxidising flame gives a bead that is blue (after cooling) because of formation of NEET level
The shape of BF3 and the hybridisation of boron in it are NEET level
BCl3 is hydrolysed rapidly by water whereas CCl4 is not, because JEE Main level
The correct order of Lewis acid strength of boron trihalides towards a given base (such as NH3) is JEE Main level
Select the correct statement(s) about boric acid. JEE Main level
An aqueous solution of borax, Na2B4O7, is alkaline because JEE Main level
In the anion [B4O5(OH)4]^2- present in borax, the numbers of sp^2 and sp^3 hybridised boron atoms are respectively JEE Main level
Heating diborane with excess ammonia (high temperature) finally gives the compound JEE Main level
Diborane is completely hydrolysed: B2H6 + 6H2O -> 2H3BO3 + 6H2. Taking atomic masses B = 11 and H = 1 and molar volume 22.4 L/mol at STP, find the volume of hyd... JEE Main level
Which of the following statements about diborane, B2H6, are correct? JEE Advanced level
Match the reactions of diborane in Column I with the products in Column II. Column I: (P) B2H6 + 6H2O; (Q) B2H6 + 3O2; (R) B2H6 + excess NH3, then heat; (S) B2H... JEE Advanced level
Consider the statements about the borax bead test: (i) a copper salt gives a blue bead in the oxidising flame; (ii) a chromium salt gives a green bead; (iii) a ... JEE Advanced level
The total number of B-O sigma bonds in one [B4O5(OH)4]^2- ion (two tetrahedral B atoms and two trigonal B atoms, five bridging oxide O atoms, four terminal OH g... JEE Advanced level
Boric acid (molar mass 62 g/mol) is heated in stages: H3BO3 -> HBO2 -> H2B4O7 -> B2O3 until only B2O3 (molar mass 70 g/mol) remains. The mass of residue from 12... JEE Advanced level
Which of the following are correct about boron trihalides? JEE Advanced level
Borax decahydrate reacts with hydrochloric acid: Na2B4O7.10H2O + 2HCl -> 4H3BO3 + 2NaCl + 5H2O. Use atomic masses Na = 23, B = 11, O = 16, H = 1. Calculate the ... JEE Advanced level