Question

Which chemical compounds of elements were used by Mendeleev to gauge their chemical similarities?

• A. A, C
• B. A, B, C
• C. B, D
• D. A, B, C, D

Answer 1

Answer: (A), (C)

The correct options are
A

A, C

C

B, D

Mendeleev considered oxides and hydrides of elements for classifying their properties. Two general formulae; one for oxides and second for hydrides; have been given for the elements of each group in the periodic table. For example: $R_2$O for oxides and RH for hydrides, of the elements of the first group. Using the given general formulae, the formula of oxides and hydrides can be written for the elements of each group. For example: hydrogen, sodium, potassium, etc. belong to the first group. The general formula of oxides for the elements of the first group is $R_2$O. Accordingly they form $H_2$​​​​​​​O, $N{a}_2$​​​​​​​O, $K_2$​​​​​​​O, etc.