Which of the following statements is true? A)Physical properties cannot be tested without changing the chemical structure of the substance.
B)The compound potassium chloride (KCl) has different properties than potassium (K) and chlorine (Cl).
C)Increasing temperature will decrease the rate of a chemical reaction.
D)Under normal conditions, atoms have a positive charge.

Explanation:

B)The compound potassium chloride (KCl) has different properties than potassium (K) and chlorine (Cl).

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.

the answers are

c and c