Suppose the mass spectrum of a hypothetical monatomic element x contains a signal at mass number 13 and another of identical height at mass number 15.
how many isotopes are present and why
what's the fractional abundance of the isotopes. why?

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