What gives carbon the ability to form chains that are almost unlimited in length?

it has 4 electrons surrounding it. Every electron wants to be bonded to another electron. That means every atom want 8 electrons total. Carbon on its own only has 4 electrons. That means it can make 4 bonds.

Explanation: it has 4 electrons surrounding it. Every electron wants to be bonded to another electron. That means every atom want 8 electrons total. Carbon on its own only has 4 electrons. That means it can make 4 bonds.

b is the correct

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.