Q.7 (i) Chalk contains calcium, carbon and oxygen in the ratio 10 : 3 : 12. Find the Percentage of carbon in chalk. (ii) If in a stick of chalk, carbon is 3 g, what is the weight of the chalk stick?

$$\therefore$$ Percentage of carbon in chalk
=$$\frac{3}{25}$$ ×100%=12%
$$\therefore$$Weight of chalk =$$\frac{3}{3}$$ × 25 g = 25 g