If a neutral atom of oxygen (o) has 8 protons, 8 electrons and 7 neutrons, what is the mass number of this atom? a.8b.15c.16d.23

B. 15

Explanation:

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

Atomic number is defined as the number of protons or number of electrons that are present in an atom.

Atomic number = Number of electrons = Number of protons

Given : number of protons = 8

number of electrons = 8

number of neutrons = 7

Hence, mass number = Number of protons + Number of neutrons = 8+ 7 = 15.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance