History Of Periodic Table

1. Dobereiner's triad was based on

Atomic mass

Atomic number

Ions

Valency

2. Position of isotope was a problem in

Mendeleev's

Newland's

Dobereiner's

3. The atomic mass of sodium if lithium - mass 7, sodium and potassium mass 39 are triads is

23

30

26

21

4. Merit of mendeleev' periodic table

Based on atomic mass

Position of isotopes

Left gaps for discovery of elements

Position of hydrogen

5. Who proposed the law of octaves?

Mendeleev

Newland

Mosely

Dobereiner

6. Demerit of Newland's classification is

Only lighter elements could be arranged

Only heavier elements could be arranged

Position of isotopes

Position of hydrogen