Question

1. Chalk contains calcium, carbon and oxygen in the ratio \(10:3:12\). Find the percentage of carbon in chalk. 
2.  If in a stick of chalk, carbon is \(3\) g, what is the weight of the chalk stick?

Answer 1

(i) Ratio of calcium, carbon, and oxygen = \(10: 3: 12\)
As \(10 + 3 +12 = 25\),
Therefore, percentage of carbon = \(\frac{3}{25}\times100=12\%\)

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(ii)  Let the weight of the stick be \(x\) \(g\).
\(12 \%\) of \(x\) = \(3\)

\(\frac{12}{100}\times x=3\)

\(x= 3\times \frac{100}{12}=25\;g\)