The basic difference between Mendeleev’s Periodic Law (A) and Modern Periodic Law (B) is:
1. | A is based on atomic weights while B is based on atomic numbers. |
2. | B is based on atomic weights while A is based on atomic numbers. |
3. | A is based on the number of isotopes while B is based on atomic numbers. |
4. | A is based on physical properties while B is based on chemical properties. |
The formula for the oxide formed by Eka-aluminum is:
1.
2.
3.
4. EO
The basic theme of the periodic table is:
1. | To classify the elements in a period according to their properties. |
2. | To classify the elements in a group according to their ionization enthalpy. |
3. | To classify the elements in periods and groups according to their properties. |
4. | To classify the elements in periods and groups according to their lustre. |
Those in a group that falls under the law of triads include:
1. Cl, Br, I
2. C, N, O
3. Na, K, Rb
4. H, O, N