Question

Chalk contain 10% calcium, 3% carbon and 12% oxygen. Find the amount (in grams) of each of these in 2 kg of chalk.

Answer 1

Answer:

Calcium: 200 grams

Carbon: 60 grams

Oxygen: 240 grams

Step-by-step explanation:

1 kg = 1000 grams (g)

Thus, we have 2000 g of chalk

Proportion of calcium = 10% = 0.10

Amount of calcium in 2000 g of chalk = 0.10 * 2000 g

                                                                = 200 g

Proportion of carbon = 3% = 0.03

Amount of carbon in 2000 g of chalk = 0.03 * 2000 g

                                                                = 60 g

Proportion of oxygen = 12% = 0.12

Amount of oxygen in 2000 g of chalk = 0.12 * 2000 g

                                                                = 240 g

More explanation:

When we say chalk has 10% calcium by mass, we mean that 100 units of chalk will contain 10 units of calcium. (% means per cent or for every 100)

10 units of calcium in 100 units of chalk

0.10 units of calcium in 1 unit of chalk

This means:

1 unit of chalk will contain 0.10 units of calcium

2 kg of chalk will contain 0.10 * 2 kg of calcium

2000g of chalk will contain 0.10 * 2000 g of calcium

2000g of chalk will contain 200g  of calcium