Question

Which of the following is correct for sodium atom (Z = 11 and A = 23)?

• A. 12 neutrons and 12 protons
• B. 11 electrons and 12 protons
• C. 11 electrons and 12 neutrons
• D. 11 neutrons and 12 electrons

Answer 1

The correct option is C 11 electrons and 12 neutrons

$\bullet$ Atomic number (Z) = number of protons present in the nucleus of an atom.
Hence, number of protons present in sodium atom is = 11.

$\bullet$ For a neutral atom, number of electrons is equal to the number of protons.

$\bullet$ Hence, number of electrons = 11

$\bullet$ Mass number (A) = number of neutrons + number of protons

$\bullet$ Number of neutrons = Mass number - number of protons = 23-11 = 12.
Hence, number of neutrons present in sodium atom is = 11.