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Ex 8.3, 7 - (i) Chalk contains calcium, carbon, oxygen in ratio 10:3:

Ex 8.3, 7 - Chapter 8 Class 7 Comparing Quantities - Part 2
Ex 8.3, 7 - Chapter 8 Class 7 Comparing Quantities - Part 3


Transcript

Ex 8.3, 7 (i) Chalk contains calcium, carbon and oxygen in the ratio 10:3:12. Find the percentage of carbon in chalk. Calcium : Carbon : Oxygen = 10 : 3 : 12 Total parts = 10 + 3 + 12 = 25 Percentage of carbon = (π‘ƒπ‘Žπ‘Ÿπ‘‘π‘  π‘œπ‘“ π‘π‘Žπ‘Ÿπ‘π‘œπ‘›)/(π‘‡π‘œπ‘‘π‘Žπ‘™ π‘π‘Žπ‘Ÿπ‘‘π‘ ) Γ— 100 = 3/25Γ— 100% = 3 Γ— 100/25 % = 3 Γ— 4% = 12% Ex 8.3, 7 (ii) If in a stick of chalk, carbon is 3g, what is the weight of the chalk stick? Given, Weight of Carbon = 3g Now, We know that Carbon 12% of chalk Weight of Carbon = 12% Γ— Weight of chalk 3 = 12% Γ— Weight of chalk 3 = 12/100 Γ— Weight of chalk 12/100 Γ— Weight of chalk = 3 Weight of chalk = 3 Γ— 100/12 Weight of chalk = 100/4 Weight of chalk = 25 So, Weight of chalk is 25 g Weight of chalk = 3 Γ— 100/12 Weight of chalk = 100/4 Weight of chalk = 25 So, Weight of chalk is 25 g

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