Exponents and Scientific Notation Word Problems for 7th Grade

A scientist measures the mass of a small particle as 3.2 x 10^-27 kg. If she has 5 such particles, what is the total mass in scientific notation?

• 3.2 x 10^-26 kg

• 1.0 x 10^-25 kg

• 6.4 x 10^-27 kg

• 1.6 x 10^-26 kg

The speed of light is approximately 3.0 x 10^8 meters per second. How long does it take light to travel 1.5 x 10^9 meters? Express your answer in seconds using scientific notation.

• 3.0 x 10^1

• 4.0 x 10^0

• 6.0 x 10^0

• 5.0 x 10^0

A bacteria culture grows at a rate of 2 x 10^3 bacteria per hour. How many bacteria will there be after 4 hours? Write your answer in scientific notation.

• 1.6 x 10^4

• 2.0 x 10^3

• 8.0 x 10^3

• 4.0 x 10^3

A comet is traveling at a speed of 2.5 x 10^4 km/h. How far will it travel in 3 hours? Provide your answer in scientific notation.

• 2.5 x 10^4 km

• 7.5 x 10^4 km

• 1.0 x 10^5 km

• 5.0 x 10^4 km

The area of a small park is 1.5 x 10^4 square meters. If the park is divided into 5 equal sections, what is the area of each section in scientific notation?

• 2.5 x 10^3

• 3.0 x 10^3

• 4.0 x 10^3

• 1.0 x 10^4

A cell phone tower can transmit signals to an area of 2.0 x 10^3 square kilometers. If there are 4 towers, what is the total area they can cover in scientific notation?

• 6.0 x 10^3

• 10.0 x 10^3

• 4.0 x 10^3

• 8.0 x 10^3

A certain virus can replicate itself 3 times every hour. If it starts with 1.0 x 10^2 viruses, how many viruses will there be after 5 hours? Express your answer in scientific notation.

• 1.5 x 10^4

• 2.43 x 10^4

• 1.0 x 10^3

• 3.0 x 10^5

The distance from Earth to the nearest star is about 4.2 x 10^16 meters. If a spaceship travels at a speed of 1.0 x 10^5 meters per second, how long will it take to reach the star? Provide your answer in scientific notation.

• 4.2 x 10^10 seconds

• 4.2 x 10^12 seconds

• 4.2 x 10^9 seconds

• 4.2 x 10^11 seconds

A factory produces 1.2 x 10^6 toys in a month. If the production doubles, how many toys will be produced in a month? Write your answer in scientific notation.

• 2.4 x 10^6

• 1.2 x 10^6

• 2.0 x 10^6

• 3.6 x 10^6

A researcher finds that a certain chemical reaction occurs at a rate of 5.0 x 10^-3 moles per liter per second. If the reaction occurs for 10 seconds, how many moles of the chemical are consumed? Express your answer in scientific notation.

• 5.0 x 10^-1

• 2.5 x 10^-2

• 5.0 x 10^-2

• 1.0 x 10^-2