Science Physical Science Flashcards

Which of the following best describes an endothermic reaction?

Answer: A reaction that absorbs energy from the surroundings

Endothermic reactions absorb heat from the surroundings, causing the environment to feel cooler.

A student pushes a box across the floor with a force of 30 N and the box moves 4 meters. How much work is done?

Answer: 120 J

Work = force × distance = 30 N × 4 m = 120 J.

What happens to the density of most solids when they are heated?

Answer: Density decreases because the volume increases while mass stays the same

Heating causes most solids to expand (increase in volume) while their mass stays constant, so density decreases.

Which law states that the total momentum of a closed system remains constant if no external forces act on it?

Answer: Law of Conservation of Momentum

The Law of Conservation of Momentum states that total momentum in a closed system is constant in the absence of external forces.

A mixture of sand and iron filings can best be separated by using:

Answer: A magnet

Iron is magnetic and sand is not, so passing a magnet over the mixture will attract and separate the iron filings.

Which of the following is true about isotopes of the same element?

Answer: They have the same number of protons but different numbers of neutrons

Isotopes are atoms of the same element with the same number of protons but differing numbers of neutrons, giving them different mass numbers.

A light ray passes from air into glass and bends toward the normal. This phenomenon is called:

Answer: Refraction

Refraction is the bending of light as it passes from one medium to another due to a change in its speed.