Chemical Reactions Practice#1

True or False
In a chemical reaction, no new atoms are created, and no atoms are destroyed. 

• true
• false

The left side of the equation below is called

• Products
• Reactants

The right side of the equation below is called the

• products
• reactants

Which statement is not a description of a chemical reaction?

• A solid is dropped into a beaker of liquid and a gas is released. You observe vapors and bubbles.

• Two clear and colorless liquids are mixed in a beaker and a cloudy substance is formed.

• A solid is dropped into a beaker of liquid and the solid changes color.

• A liquid is heated and half of it evaporates.

Which of the following is NOT a sign of a chemical reaction?

• Color changes

• Cutting into fourths

• Heat is produced

• Gas is formed

In a chemical reaction

• The atoms of the reactants always stay together to form the products
• The atoms of the reactants unbond, rearrange, and then rebond to form the products
• New atoms are formed which combine to make the products
• Some atoms disappear while others multiply to form the products

Which is the best evidence of a chemical reaction?

• a solid is dissolved into a liquid

• a solid melts to form a liquid

• formation of a solid (precipitate) after two solutions are combined

• substances bend and change shape

Which of the following is true about chemical reactions?

• atoms will be created and destroyed

• only occur outside living organisms

• occur only in living organisms

• new pure substances are made from atoms

Which of the following are the correct product(s) for the reaction between magnesium and oxygen?

• MgO

• Mg + O

• Mg

• CO₂

Iron reacts with solid sulfur to produce iron(II) sulfide powder. Which of the following is the correct formula for iron(II) sulfide?

• Fe₂S

• FeS

• Fe₂S₂

• Fe₂S