Question

chalk contains 10 % calcium, 3% carbon ,12% Oxygen and the remaining sand. find the amount of carbon and calcium in grams in
$2 \times 1 \div 2$
kg of chalk also find the a amount of sand

Answer 1

total percentage is 10+3+12 = 25
amount of calcium = 25 x 10 / 100
= 2.5 grams
amount of carbon = 25 x 3 / 100
= 0.75 grams
.. now ca, c and oxygen are 25 percent which means remaining 75 is sand , (100-25)
so, 75 x 25 /100 = 18.75 grams is sand

Answer 2

Answer: The chalk have 75g of carbon 250g of calcium and 1 kg 875 g of sand

Step-by-step explanation:

Calcium in chalk = 10%

Carbon in chalk= 3%

Oxygen in chalk = 12%

Sand= 100%-(calcium+carbon+oxygen)=100%- (10%+3%+12%)= 75%

$Chalk =2\dfrac{1}{2} kg = \dfrac{5}{2} kg$

$Carbon = 3\% \text { of } chalk = \dfrac{3}{100} \times \dfrac{5}{2} =\dfrac{3}{40} kg=\dfrac{3}{40} \times 1000 g = 75g$

 $Calcium= 10\% \text{ of } chalk=\dfrac{10}{100} \times \dfrac{5}{2} = \dfrac{1}{4} kg = \dfrac{1}{4}\times 1000g= 250g$

$Sand =75\% \text{ of } chalk =\dfrac{75}{100} \times \dfrac{5}{2} =\dfrac{15}{8} kg \\\\=\dfrac{15}{8} \times 1000g= 1875g =\text { 1 kg 875 gm}$

Hence, the chalk have 75g of carbon 250g of calcium and 1 kg 875 g of sand