The movement of the liquid in a thermometer shows changes in temperature. An increase in temperature indicates the molecules in the liquid (A) moved slower and closer together (B) contracted in size when heated (C) moved faster and spread farther apart (D) expanded in size when heated

D. Expanded in size when heated

that liquid may be mercury

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.  

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