Science MCQs

Elements in a group have the same number of valence electrons (electrons in the outermost shell) which gives them similar chemical properties.

Group 18 contains the noble gases which are inert due to their stable electron configuration.

Group 1 elements (e.g. Li Na K) are known as the alkali metals.

The maximum number of electrons is given by 2n². For n=2 it is 2*(2)² = 8.

The first shell (K) holds 2 electrons. The second shell (L) holds 8 electrons. The remaining 1 electron goes to the third shell (M) giving 2 8 1

Carbon has an atomic number of 6.

The atomic number of Magnesium is 12 which is equal to its number of protons.

Number of neutrons = Mass Number (A) - Atomic Number (Z) = 19 - 9 = 10.

The maximum number of electrons that can occupy a shell is given by the formula 2n² where n is the shell number.

The number of protons (atomic number) defines which element an atom is.