Short Answer Type
Long Answer TypeExplain structures of diborane. Write the structures of diborane and explain the nature of bonding in it ?
Short Answer TypeA certain salt X, gives the following results:
It aqueous solution is alkaline to litmus.
A certain salt X, gives the following results:
It swells up to a glassy material Y on strong heating.
A certain salt X, gives the following results:
When conc. H2SO4 is added to a hot solution of X, white crystals of an acid Z separate out.
How is orthoboric acid prepared?
Orthoboric acid is also called boric acid (H3BO3) and prepared as follows:
(i) From borax: It may be prepared by adding an excess of sulphuric acid or hydrochloric acid to a hot saturated solution of borax.
On cooling the reaction mixture, crystals of boric acid separate out.
(ii) From colemanite: The mineral is powdered, mixed with boiling water and sulphur dioxide is passed through the mixture.
On cooling, the reaction mixture, crystals of boric acid separate out.
(iii) From colemanite: The mineral is powdered, mixed with boiling water and sulphur dioxide is passed through the mixture. 
On crystallisation, boric acid separates out while calcium sulphite remains in solution.
Boric acid can be purified by recrystallization.
(iv) From boron halides: When boron halides are hydrolysed, orthoboric acid is formed. 
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