The correct global electron configuration of the anion 9 F -1 corresponds to: A) 1s 2 2s 2 3p 6 B) 1s 2 2s 2 2p 6 C) 1s 2 2s 3 2p 5 D) 1s 1 2p 6 3p 2

i think it is true since you can test the answer and can use observations to complete it.

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.  

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.