An empty container has a mass of 0.6 kg.
When the container is full of rice, it has a mass of 18.6 kg.
The average mass of a grain of rice is 2 x 10-2 g.
Use this information to work out how many grains of rice are in the container.
Give your answer in standard index form.

There are 9 × 10^5 grains of rice in the container.

Step-by-step explanation:

Mass of empty container = 0.6 kg

Mass of container filled with rice = 18.6 kg

⇒ Mass of rice = 18.6 - 0.6 = 18 kg

Mass of one grain of rice = 2 × 10^-2 g = 2 × 10^-2/10³ kg (∵ 1 kg = 1000 g)

                                          = 2 × 10^-5 kg

⇒ Number of grains of rice = Total Mass of rice/Mass of 1 grain

                                             = 18/2 × 10^-5

                                             = 9 × 10^5 grains of rice