# Tincal contains mainly

$\begin{array}{1 1}(a)\;NaNO_3&(b)\;Na_2B_4O_7.10H_2O\\(c)\;Na_2CO_3&(d)\;Na_2SO_4\end{array}$

Tincal contains mainly $Na_2B_4O_7.10H_2O$
Hence (b) is the correct answer.