Electrolysis uses electrical current to break water molecules in to oxygen gas and hydrogen gas. how do you know that this is a chemical change? a. their is a phase change from liquid to gas b. it is a single replacement action c. electric current always causes a chemical change d. chemical bonds in the water molecule are broken

Chemical bonds in the water are broken.
Water is made of hydrogen and oxygen. If an electric current is applied it breaks the compound down into its individual elements that is a chemical change.

i dont know

explanation:

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.