A second feature of H2O molecules is that they behave differently from most molecule when heated or cooled.
Most materials expand when heated and contract when
cooled. Water contracts when cooled until reaches 4°C.
(Water freezes at 0° Celsius.) As it continues to cool, water
reverses and begins to expand.

what is the comparison inherent in this paragraph?

A. At freezing , h2O molecules expand rather than contract as most molecules .

B. H2O molecules behave different from other molecules.

C. Most molecules expand when heater & contract when cooled .

first one is the correct answer

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

it takes on an electronical energy