chemical reactions and more

what is physical change?

• its when new substance are made.

• its when there is no new substances made

• i dont know

• ice melting.

what is chemical change?

• when 2 elements are joined together to make new substances.

• when 2 elements are joined but don't make new substance.

what do we use to make chemical reaction speed up.

• catalyst

• water

• hydrogen

• dioxide

is burning wood chemical reaction?

• yes

• no

ice breaking a pencil are physical reaction?

• yes

• no

what is thermal decomposition?

• when substance breaks down because of heat.

• when substance breaks down because of cold.

• when substance breaks down because of oxygen.

• when substance breaks down because of hydrogen.

what do we need for thermal decomposition to work?

• Heat energy
• Water
• Light energy
• solar energy

what is endothermic reaction?

• An endothermic reaction is a chemical reaction that takes in heat from the surroundings.

• An endothermic reaction is a chemical reaction that takes out heat from the surroundings.

what is exothermic reaction?

• An endothermic reaction is a chemical reaction that takes out heat from the surroundings.

• An endothermic reaction is a chemical reaction that takes in heat from the surroundings.

what is reactant?

• A substance that remains unchanged during a reaction
• A substance that is produced by a reaction
• A substance that has no role in a reaction
• A substances that needed to be joined in chemical reaction