What volume is needed to store 0.050 moles of helium gas at 202.6 kpa and 400 k? (given: r = 8.314 l∙kpa/k∙mol)
a) 1.218 l
b) 121.8 l
c) 0.820 l
d) 8.21 l
e) 82.1 l

african americans demonstrated their newly found freedom by relocating often in search of relatives whom they had been separated from during slavery. others established schools to educate freed people and they built institutions such as churches and political organizations to advocate for their rights.

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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