# Chalk contains 10% calcium, 3% carbon and 12% oxygen. Find the amount of carbon and calcium (in grams) in 2 1/2 kg of chalk.

**Solution:**

Given, chalk contains 10% calcium, 3% carbon and 12% oxygen.

We have to find the amount of carbon and calcium (in grams) in 2 1/2 kg of chalk.

Percentage of calcium = 10%

Percentage of carbon = 3%

Percentage of oxygen = 12%

We know, 1 kg = 1000 gm

2 1/2 kg = 2(1000) + 500

= 2000 + 500

= 2500 gm

According to the question,

In 2500gm of chalk,

Amount of calcium = 10% of 2500

= (10/100) × 2500

= 10 × 25

= 250 gm

Amount of carbon = 3% of 2500

= (3/100) × 2500

= 3 × 25

= 75 gm

Therefore, the amount of calcium and carbon is 250 gm and 75 gm.

**✦ Try This: **The weight of a sand bag is 40 kg. In a hurry it weighed 40.8 kg. What is the percentage of error?

**☛ Also Check: **NCERT Solutions for Class 7 Maths Chapter 8

**NCERT Exemplar Class 7 Maths Chapter 7 Problem 102**

## Chalk contains 10% calcium, 3% carbon and 12% oxygen. Find the amount of carbon and calcium (in grams) in 2 1/2 kg of chalk.

**Summary:**

Chalk contains 10% calcium, 3% carbon and 12% oxygen. The amount of carbon and calcium (in grams) in 2 1/2 kg of chalk are 250 gm and 75 gm.

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