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. 

Subtopic:   Evolution of Periodic Table |
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The formula for the oxide formed by Eka-aluminum is:

1. EO4

2. E2O3

3. E3O2

4. EO

Subtopic:   Evolution of Periodic Table |
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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.

Subtopic:   Evolution of Periodic Table |
 87%
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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

Subtopic:   Evolution of Periodic Table |
 63%
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