Which of the following is true about an atom of lithium and an atom of helium

c

Explanation:

they have different numbers of protons (you can see this on the periodic table becasue they have different atomic numbers)

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

i do not get it   at all