(plz anwser all questions 15 points)

question 1: check all the statements that are correct. conservation of mass means:

a: we can start a reaction with different types of elements than we have at the end of the reaction.

b: matter cannot be created

c: matter can be destroyed in a chemical reaction

d: we must start and end with the same amounts of matter

question 2: select all of the signs of a chemical reaction

a: a gas is released

b: a solid is formed

c: a temperature change happens

d: the change can be easily undone

e: the state of matter changes

f: a color change happens

1. B, D,

2.A, F

Explanation:

1. According to the law of conservation of mass, In a course of chemical reaction, matter can neither be created nor destroyed but can be changed from one form to another. This means the amount of matter at the begining and ending of a reaction must be thesame.

2. Chemical reaction is not easily reversible. when gas is produced, provided the reaction system is an open system, the gas cannot be recovered and the reactants cannot be recovered from the products. likewise color change are attributed to chemical reaction

fdvwsa gfwsargebgeebbfwfwffw gwf   vgwgw gw f gwgw fgw v v dsv dwfff

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?