A) >7
B) 6 > 7
C) 7
D) < 7
Correct Answer: A
Solution :
Sodium borate \[(N{{a}_{3}}B{{O}_{3}})\] is the salt of weak acid and strong base. On hydrolysis sodium borate give NaOH and \[{{H}_{3}}B{{O}_{3}}\]. \[\underset{sodium\text{ }borate}{\mathop{N{{a}_{3}}B{{O}_{3}}}}\,\,\,+3H.\,OH\,\,\,\underset{\begin{smallmatrix} sodium\text{ }hydroxide \\ strong\text{ }base \end{smallmatrix}}{\mathop{3NaOH}}\,\] \[\underset{\begin{smallmatrix} boric\text{ }acid \\ weak\text{ }acid \end{smallmatrix}}{\mathop{+{{H}_{3}}B{{O}_{3}}}}\,\] As NaOH is strong base, it remains ionized upto greater extent. Thus, the solution becomes basic hence, pH of solution is greater than seven, ie, pH > 7.
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