⇒ Number of given elements are 8. They are A,B,C,D,E,F,G and H.
⇒ All 8 elements are belongs to same period because they have same number of electronic shells and have different number of electrons in the outermost shell.
⇒ We can see the above pattern in 3rd period as it have 8 elements.
⇒ Nature of compound formed by a combination of element B and F is ionic in nature since B is metal and F is non-metal.
⇒ Here ⇒ A=Na (Sodium), B=Mg (Magnesium),
C=Al (aluminium), D=Si (Silicon),
E=P (Phosphorus), F=S (Sulphur),
G=Cl (Chlorine), H=Ar (Argon).