revision lesson 3,4

H2 (g)
what is (g) realated to ?

• gas

• gravity

is a way to describe the chemical reaction

are any atoms created or destroyed in this reaction (yes or no)

how many atoms of hydrogen are in one molecule of ammonia ?

how many reactant are there

the balanced element in this equation is .....

a system in which the maters can’t enter or leave

a system in which the matter can enter from of escape to the surrounding

Match the following

• Replacement

• 
• Decomposition

• 
• synthesis

• 

according to the law of conservation of mass, chemical equation must be balanced ?

• true

• false