classification of elements

Pick out the chemically most reactive elements from the given triads.Li, Na, K F, Cl, Br

• (a) Li and F

• (b) Li and Br

• (c) K and F

• (d) K and Br

Newlands relation is called

• a) Musical Law

• (b) Law of Octaves

• (c) Periodic Law

• (d) Atomic Mass Law

Pick out the chemically most reactive elements from the given triads.

• (a) Li and F

• (b) Li and Br

• (c) K and F

• (d) K and Br

Up to which element,law of octaves found to be applicable

• Oxygen

• Calcium

• Cobalt

• Potassium

Which one of the following elements do not constitute a Doebereiner's triad ?

• Cl,Br, I

• Li,Na,K

• S,Se,Te

• N,P,As

The most significant contribution towards the development of periodic table was made by

• Mendeleev.

• Avogadro.

• Dalton.

• Cavendish.

The number of elements known at present is ___.

• 31

• 114

• 63

• 75

Law of Triads was referred to as ___ relationship.

• Lothar Meyer's

• Mendeleev's

• Newlands's

• Dobereiner's

In which order do we need to put barium, calcium, and strontium for Dobereiner's Law of Triads to apply?

• calcium, strontium, barium

• barium strontium calcium

• strontium barium calcium

• stontium calcium barium

how many triads are invented by dobereiner among the the elements of his time

• 5

• 3

• 2

• 4