The atomic numbers of three elements A, B and C are 12, 18 and 20 respectively. State, giving reason, which two elements will show similar properties.
The elements are,
A-(Atomic number 12) = Magnesium
B-(Atomic number 18) = Argon
C-(Atomic number 20) = Calcium
Element Calcium and magnesium will show similar properties as they belong to same group (Group II) of the periodic table. They have same number of valence electrons and they both are metals. While argon is a noble gas.