Chemical Changes part 1

Which of the following is a sign that a chemical reaction has occurred?

• change in shape
• melting
• formation of a gas
• dissolving

what is the definition of chemical change?

• any change that results in the formation of new chemical substances. 
• changing clothes
• matter cannot be created or destroyed, only change form
• changes affecting the form of a chemical substance, but not its chemical composition.

When sugar is heated, what is the type of reaction happening?

• thermal decomposition

• combustion

• oxidation

What are the products of combustion?

• oxygen

• carbon dioxide

• heat

• water

When sodium burns in oxygen, what is the name of the product?

Which reaction involves the interaction between matter and light?

• combustion

• respiration

• photosynthesis

Electrolysis can cause the following effects except for

• decomposing water

• electroplating a coin

• decompose sugar using heat

In photographic films, what causes the dark areas on the film?

• decomposition of silver

• decomposition of silver bromide

• decomposition of bromine

What is the process by which the cells in living organisms (plants and animals) get energy?

At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?

• the product is doubled

• the product is half the mass of the reactants

• the mass is the same

• the mass changes depending on the reaction

Answer explanation

The total mass of the reactants is equal to the total mass of the products due to the law of conservation of mass in chemical reactions.