Question

Let a partially dried clay mineral contains $8\%$ water. The original sample contains $12\%$ water and $45\%$ silica and $43\%$ aluminium. The $\%$ of silica in the partially dried sample is nearly

• A. $50\%$
• B. $49\%$
• C. $55\%$
• D. $47\%$

Answer 1

The correct option is D $47\%$

$\text{Initial stage}:AluminiumSilicaWater$
$43\%45\%12\%$
$\text{Final stage}(92-x)\%x\%8\%$
Ratio of silica and aluminium will remain constant, before and after drying
$\therefore \frac{45}{43}=\frac{x}{92-x}x=47\%$