8th Grade SOL Prep: PS.2 Level 1

Front

Who is credited with the discovery of the electron?

Back

J.J. Thomson

Answer explanation

J.J. Thomson is credited with the discovery of the electron in 1897 through his experiments with cathode rays, demonstrating that they were composed of negatively charged particles, which he named electrons.

Front

What is the atomic number of carbon?

Back

6

Answer explanation

The atomic number of an element is defined as the number of protons in its nucleus. Carbon has 6 protons, which gives it an atomic number of 6. Therefore, the correct answer is 6.

Front

Which of the following best describes the kinetic molecular theory?

Back

Matter is made up of particles that are in constant motion.

Answer explanation

The kinetic molecular theory states that matter is composed of particles that are always in constant motion, which explains the behavior of gases, liquids, and solids. The correct choice reflects this fundamental principle.

Front

Which scientist proposed the planetary model of the atom?

Back

Niels Bohr

Answer explanation

Niels Bohr proposed the planetary model of the atom, which describes electrons orbiting the nucleus in defined paths, similar to planets around the sun. This model improved upon earlier atomic theories.

Front

What is the symbol for the element with atomic number 8?

Back

O

Answer explanation

The element with atomic number 8 is oxygen, which is represented by the symbol 'O'. The other options correspond to carbon (C), nitrogen (N), and hydrogen (H), which have different atomic numbers.

Front

According to the kinetic molecular theory, what happens to the particles of a gas when the temperature increases?

Back

They move faster.

Answer explanation

According to the kinetic molecular theory, an increase in temperature causes gas particles to gain energy, resulting in faster movement. Therefore, the correct answer is that they move faster.

Front

Who is known for the gold foil experiment that led to the discovery of the atomic nucleus?

Back

Ernest Rutherford

Answer explanation

Ernest Rutherford is known for the gold foil experiment conducted in 1909, which led to the discovery of the atomic nucleus, disproving the plum pudding model proposed by J.J. Thomson.

Front

Which element is located in Group 1 of the periodic table?

Back

Sodium

Answer explanation

Sodium is located in Group 1 of the periodic table, known as the alkali metals. Helium and argon are noble gases in Group 18, while chlorine is a halogen in Group 17.

Front

What is the main idea of the kinetic molecular theory?

Back

Particles are always in motion.

Answer explanation

The kinetic molecular theory states that all particles are in constant motion, regardless of temperature. This means that the correct choice is that particles are always in motion, as they do not become stationary.

Front

Which scientist is associated with the development of the periodic table?

Back

Dmitri Mendeleev

Answer explanation

Dmitri Mendeleev is credited with creating the first widely recognized periodic table, organizing elements by atomic mass and properties, which laid the foundation for modern chemistry.