Chemistry Review Test

1. What is the atomic number of carbon?

• 8

• 12

• 3

• 6

Answer explanation

The atomic number of carbon is 6, which corresponds to the number of protons in its nucleus.

What is the chemical formula for water?

• NaCl

• H2O

• CO2

• CH4

Answer explanation

The chemical formula for water is H2O. It represents two hydrogen atoms bonded to one oxygen atom.

Tags

NGSS.MS-PS1-1

1. Identify the type of bond formed between sodium and chlorine in sodium chloride.

• Metallic bond

• Hydrogen bond

• Ionic bond

• Covalent bond

Answer explanation

Sodium and chlorine form an ionic bond in sodium chloride. Ionic bonds occur between a metal and a nonmetal, where electrons are transferred from the metal to the nonmetal, resulting in the formation of charged ions.

Tags

NGSS.HS-PS1-3

What is the chemical formula for methane?

• CH4

• CO2

• H2O

• C6H12O6

Answer explanation

The chemical formula for methane is CH4. It consists of one carbon atom (C) bonded to four hydrogen atoms (H).

Tags

NGSS.MS-PS1-1

Which of the following is a noble gas?

• Oxygen

• Nitrogen

• Carbon

• Helium

Answer explanation

Helium is a noble gas.

What is the mass number of an atom?

• Total number of electrons

• Total number of protons and neutrons

• Total number of neutrons

• Total number of protons

Answer explanation

The mass number of an atom is the total number of protons and neutrons.

What is the formula for calculating density?

• mass x volume

• density/mass

• mass/volume

• volume/mass

Answer explanation

Density is calculated by dividing the mass of an object by its volume. Therefore, the correct formula for calculating density is mass/volume.

What is the process of converting a gas into a liquid called?

• Sublimation

• Evaporation

• Condensation

• Solidification

Answer explanation

The process of converting a gas into a liquid is called condensation. During condensation, the gas molecules lose energy and come together to form a liquid.

Tags

NGSS.MS-PS1-4

Which of the following is a halogen?

• Carbon

• Sodium

• Chlorine

• Oxygen

Answer explanation

Chlorine is a halogen because it belongs to Group 17 of the periodic table and has properties similar to other halogens like fluorine and bromine.

What is the balanced chemical equation for the reaction between hydrogen and oxygen to form water?

• H₂ + O₂ -> H₂O

• 2H₂ + O₂ -> 2H₂O

• H + O -> H₂O

• 1. H₂O -> H + O₂

Answer explanation

The balanced chemical equation for the reaction between hydrogen and oxygen to form water is 2H2 + O2 -> 2H2O. This equation represents the correct choice, where two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5