8th Grade Semester Exam Review

Front

What is the formula for calculating force?

Back

Force = mass x acceleration

Front

Why do some substances float on water?

Back

They are less dense than water.

Front

What does the Hertzsprung-Russell diagram illustrate?

Back

It shows the relationship between the brightness and temperature of stars.

Front

What is serotonin?

Back

Serotonin is a neurotransmitter that helps relay messages in the human brain.

Front

How many atoms are in a molecule of serotonin (C10H12N2O)?

Back

25 atoms.

Front

What is the chemical formula for methane?

Back

CH4

Front

What is density?

Back

Density is the mass of an object divided by its volume.

Front

What is the relationship between temperature and the density of substances?

Back

Generally, as temperature increases, density decreases.

Front

What is the significance of the Hertzsprung-Russell diagram in astronomy?

Back

It helps classify stars and understand their evolution.

Front

What is a neurotransmitter?

Back

A neurotransmitter is a chemical substance that transmits signals across a synapse from one neuron to another.