Electrolysis uses electrical current to break water molecules in to oxygen gas and hydrogen gas. how do you know that this is a chemical change? a. their is a phase change from liquid to gas b. it is a single replacement action c. electric current always causes a chemical change d. chemical bonds in the water molecule are broken

Chemical bonds in the water are broken.
Water is made of hydrogen and oxygen. If an electric current is applied it breaks the compound down into its individual elements that is a chemical change.

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.

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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.  

all eukaryotic cell have mitochondria : )