Chemistry Competition 2021

Which of the following phases of matter as the highest kinetic energy (besides plasma)?

• Gas

• Liquid

• Solid

Which of the following states of matter has the highest potential energy?

• Gas

• Liquid

• Solid

A physical substance that has mass and occupies space is called what?

• Radiation

• Matter

• Darkmatter

Which type of chemical formula always matches its structural formula (diagram)?

• Molecular

• Empirical

Which of the following are characteristics of the ball-and-stick model?

• Proportional atom sizes

• Equal atom sizes

• Bonds shown as cylindrical connections

• Atoms are spherical

What is true of physical changes?

• They are reversible

• They are chemical reactions

• They change a substance's composition

• They change a substance's phase

Select all that are physical changes

• Water boiling

• Food digesting

• Wood cutting

• Fuel burning

Most chemical reactions are

• irreversible

• reversible

What is true of chemical changes?

• They are chemical reactions

• They cannot be readily measured

• Most are irreversible

• Most are reversible

Select all that are chemical changes

• Food digesting

• Salt formation

• Water freezing

• Molten metal solidifying