7th Grade Science Fall Semester Exam

Front

What does the subscript '3' in the chemical formula Al₂O₃ indicate?

Back

There are 3 oxygen atoms in the molecule.

Front

What is the average speed for a boat that travels 20 kilometers downstream in 2 hours and returns upstream in 4 hours?

Back

6.67 km/h

Front

When a substance undergoes a physical change, what remains unchanged?

Back

The composition.

Front

What is the difference between speed and velocity?

Back

Speed is a scalar quantity that measures how fast an object is moving without considering direction, while velocity is a vector quantity that includes both the speed and the direction of motion.

Front

What method of thermal energy transfer is the direct transfer of heat between particles within a substance that are in direct contact?

Back

Conduction.

Front

What is the definition of conduction?

Back

The transfer of heat through direct contact of particles.

Front

What is the definition of convection?

Back

The transfer of heat through the movement of fluids (liquids and gases).

Front

What is the definition of radiation?

Back

The transfer of heat in the form of electromagnetic waves.

Front

What is a scalar quantity?

Back

A quantity that has only magnitude and no direction.

Front

What is a vector quantity?

Back

A quantity that has both magnitude and direction.