If you needed to dilute 18M hydrochloric acid for use in a lab needing 500 mL of 3 M HCl, how much of the highly concentrated HCl would you have to add to the water? How much water would you need to pour in first?

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

1 a

2 d

3 a

4 c

explanation:

the answer for sodium is 0.186

the answer for rubidium is 0.251