chemistry review

Which subatomic particles are in the nucleus? Check all that apply.

• Electrons

• Neutrons

• Protons

• None of the above

Where are electrons located in an atom?

• Outside the nucleus

• Inside the nucleus

• Electrons don't exist in atoms

What type of charge does a proton have?

• Positive

• Negative

• No charge

What type of charge does an electron have?

• Positive

• Negative

• No Charge

How do you find the number of neutrons in an atom?

• It is the same as the atomic mass.

• It is the same as the atomic number.

• Round the atomic mass and subtract the number of protons.

• You guess.

Which of the following is a chemical change?

• Baking brownies

• Melting ice

• Folding paper

• Painting a wall

Which of the following is a physical change?

• Baking cookies

• Rust forming on a bike

• Sharpening a pencil

• Hydrogen and oxygen creating water.

What is the law of conservation of mass?

• Mass cannot be created nor destroyed in a chemical reaction.

• Mass can be created but not destroyed in a chemical reaction.

• Mass can be destroyed but not created in a chemical reaction.

• Mass can be created and/or destroyed in a chemical reaction.

Balance this equation: K + O₂ → K₂O

• 4K + 8 O₂ → 16 K₂O

• 4K + 1 O₂ → 2K₂O

• K₂ + O₂ → K₂O₂

• 2K + O₂ → K₂2O

Balance this equation:

NaH + BF₃ → B₂H₆ + NaF

• 6 NaH + 2 BF₃ → 1 B₂H₆ + 6 NaF

• 3 NaH + 2 BF₃ → 2 B₂H₆ + 1 NaF

• 1 NaH + 1 BF₃ → 1 B₂H₆ + 1 NaF

• 2 NaH + 3 BF₃ → 1 B₂H₆ + 5 NaF