Which of the following is true about two neutral atoms of the element zinc? they will always have different masses. electrons are missing in both the atoms. both have an equal number of protons. they have different properties.

It isn't specified which neutral atom of zinc it pertains to. There are 5 stable isotopes of Zinc. It could be any of those. However, one thing is true for all possible conditions. These neutral atoms would have the same number of protons because they are of the Zinc element. It would always have 30 protons when neutral. So, the answer is: Both have an equal number of protons.

Engineers have contribute to society in many ways like making the technology we use today or any type of power energy material

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)