BECE Science 2010 Paper

Concept:In a nuclear symbol $\mathrm{^{A}_{Z}X}$, the top number $A$ is the mass number and the bottom number $Z$ is the atomic number.Mass number $=$ protons $+$ neutrons.Explanation:Here, the element is carbon, whose atomic number is $6$.So the symbol should be written as $\mathrm{^{12}_{6}C}$.Thus, number of protons $=6$.Mass number $=12$.Let the number of neutrons be $N$.Then, $12 = 6 + N$.$N = 12 - 6$.$N = 6$.Answer:There are $6$ neutrons in the nucleus of the carbon atom.The correct option is C. 6.