Chemistry Pre-Assesment

Which subatomic particle has a negative charge?

• proton

• neutron

• positron

• electron

Answer explanation

The subatomic particle with a negative charge is the electron.

What is the atomic number of carbon?

• 5

• 8

• 6

• 7

Answer explanation

The atomic number of carbon is 6, so the correct choice is 6.

Which of the following is a correct electron configuration for a neutral oxygen atom?

• 1s2 2s3 2p3

• 1s2 2s2 2p4

• 1s2 2s1 2p5

• 1s2 2s2 2p3

Answer explanation

The correct electron configuration for a neutral oxygen atom is 1s2 2s2 2p4, which represents the distribution of electrons in the atom's energy levels.

Tags

NGSS.HS-PS1-1

In which type of bond are electrons shared equally between atoms?

• Ionic bond

• Metallic bond

• Hydrogen bond

• Nonpolar covalent bond

Answer explanation

In a nonpolar covalent bond, electrons are shared equally between atoms, resulting in a balanced distribution of charge.

What is the molar mass of NaCl (sodium chloride)? (Atomic masses: Na = 23, Cl = 35)

• 58

• 50

• 60

• 45

Answer explanation

To find the molar mass of NaCl, add the atomic masses of Na and Cl: 23 (Na) + 35 (Cl) = 58. Therefore, the molar mass of NaCl is 58.

• True or False: An element’s chemical properties are largely determined by its number of neutrons.

• True

• False

Answer explanation

False - An element's chemical properties are largely determined by its number of protons, not neutrons.

• True or False: The law of conservation of mass states that mass can be created or destroyed in chemical reactions.

• True

• False

Answer explanation

False - The law of conservation of mass states that mass cannot be created or destroyed in chemical reactions.

Tags

NGSS.HS-PS1-7

• True or False: In a chemical reaction, the reactants are always on the left side of the equation.

• False

• True

Answer explanation

True because in a chemical reaction, the reactants are always written on the left side of the equation, while the products are on the right side.

• True or False: The pH scale ranges from 0 to 14, with 7 being neutral.

• True

• False

Answer explanation

True because the pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 are acidic, and above 7 are basic.

6. True or False: A catalyst is a substance that increases the rate of a chemical reaction by being consumed in the process.

• True

• False

Answer explanation

False - A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.

Tags

NGSS.HS-PS1-5