Achange in which factor will affect the rate of reaction only when gases are involved?
temperature
pressure
surface area
concentration

Pressure

Gases are the only state of matter that are affected by changes in pressure when it comes to rate of reaction. Solids and liquids are not affected by changes in pressure.

not clear

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e