Physical and chemical properties are used to describe and identify matter. Physical properties can be observed without changing the identity of the substance. Chemical properties can be observed by attempting to change the identity of a substance. What are two physical and chemical properties that you can use to help you identify a substance?

Extensive properties, such as mass and volume, depend on the amount of matter that is being measured. ... Both extensive and intensive properties are physical properties, which means they can be measured without changing the substance's chemical identity

1 a

2 d

3 a

4 c

explanation:

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.