STAAR Science 8th Grade Review

Front

What is the atomic number of Nitrogen and Oxygen combined?

Back

15 (Nitrogen has 7 protons and Oxygen has 8 protons, totaling 15 protons).

Front

In the reaction CH₄ + 2O₂ → CO₂ + 2H₂O, how many hydrogen atoms are produced?

Back

4 (There are 2 water molecules produced, each containing 2 hydrogen atoms).

Front

List the components of the universe from smallest to largest.

Back

Planets, stars, nebulae, galaxies.

Front

What type of energy transformation occurs when a match is struck against sandpaper?

Back

Chemical energy stored in the match changes to thermal energy and light energy.

Front

How do you determine which side of a hill is steeper?

Back

By comparing the angle of elevation; the side with a greater angle is steeper.

Front

What is the definition of a galaxy?

Back

A galaxy is a massive system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity.

Front

What is the law of conservation of mass?

Back

In a chemical reaction, mass is neither created nor destroyed; it is conserved.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change alters the form of a substance but not its chemical composition, while a chemical change results in the formation of new substances.

Front

What is the formula for calculating the number of atoms in a molecule?

Back

Count the subscripts in the chemical formula; for example, in H₂O, there are 2 hydrogen atoms and 1 oxygen atom.

Front

What is the definition of thermal energy?

Back

Thermal energy is the total kinetic energy of particles in a substance, related to temperature.