A student wants to examine a substance without altering its composition. Which of the following describes a property of the substance that the student should examine?

Toxicity, because it can be observed by altering the state of the substance
Boiling point, because it can be observed by altering the state of the substance
Toxicity, because it can be observed by replacing the atoms of the substance with new atoms
Boiling point, because it can be observed by replacing the atoms of the substance with new atoms

Physical property is defined as the property of a substance which becomes evident during physical change in which there is alteration in shape, size etc. No new substance gets formed during physical change. Example: Melting point

Chemical property is defined as the property of a substance which becomes evident during chemical change in which a change in chemical composition takes place. A new substance is formed in these reactions. Example: Reactivity with other substances

Thus Boiling point is a propertywhich can be examined without altering the composition, because it can be observed by altering the state of the substance