Science quiz

Which is/are evidence(s) for a chemical reaction?

• Evolution of light or heat

• Your phone

• Colour change

Which is an example of a chemical equation?

• Exothermic

• 2H₂+O₂= 2H₂O

• Endothermic

What is the third step for balancing an equation

• Do an experiment

• Write down the equation

• Count the number of atoms of each element in the reactants and the products.

• calculate its weight

Wich is greater? Activation energy or thermal energy?

• thermal energy

• activation energy

What are the types of reactions?

What is addition reaction?

• two or more substances chemically combine to form a new explosion

• two or more substances chemically combine to form a new substance

• two or more substances chemically combine to form a new compound

What is Decomposition reaction?

• A chemical reaction in which two compounds are broken built up to produce two or more smaller compounds

• A physical reaction in which a single compound is broken down to produce two or more smaller compounds

• A chemical reaction in which a single compound is broken down to produce two or more smaller compounds

What is a precipitate?

• A solid product that comes out of solution in a physical reaction.

• ​to take part in or become involved in an activity

• A solid product that comes out of solution in a chemical reaction.

• A compound that comes out of solution in a chemical reaction.

What is a nuclear reaction?

• a process that doesn't changes the nucleus of an atom but may turn one element into a completely different element.

• A big explosion

• a process that changes the nucleus of an atom and may turn one element into a completely different element.

In an hot pack, is there an endothermic or an exothermic reaction?

• endothermic reaction

• exothermic reaction