1.

A certain salt `(X)` gives the following tests : (a) Its aqueous solution is alkaline to litmus. (b) On strong heating. It sweels to give a glassy bead. ( c) When conc `H_(2) SO_(4)` is added to a hot concentrated solution of `(X)`, white crystals of a weak acid separates out. Identify `(X)` and write down the chemical equations for reaction at steps `a, b` and `c`.A. VioletB. BlueC. BrownD. White

Answer» Correct Answer - D
`(X)` is borax, `Na_(2)B_(4)O_(7).1 H_(2)O`.
(i) `Na_(2)B_(4)O_(7)+7H_(2)O hArr underset(("strong base"))(2NaOH)+underset(("Weak acid"))(4H_(3)BO_(3))`
Due to present of `NaOH`, the aqueous solution is alkaline to litmus.
(ii) `Na_(2)B_(4)O_(7).10H_(2)to2NaBO_(2)+underset("Glassy bead")B_(2)O_(3)`
(iii) `Na_(2)B_(4)O_(7)+H_(2)SO_(4)+5H_(2)OtoNa_(2)SO_(4)underset("White crystals")4H_(3)BNO_(3)`


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