It was found that the law of octaves was applicable only up to:

Elements have been arranged in the following sequence on the basis of their increasing atomic masses.
$F, Na, Mg, Al, Si, P, S, Cl, Ar, K$
$(a)$ Pick two sets of elements which have similar properties.
$(b)$ The given sequence represents which law of classification of elements?

Write true or false for the statement: It was assumed by Newlands that only $63$ elements existed in nature and no more elements would be discovered in the future.

Can the following groups of elements be classified as Dobereiner's triad?
$(a)$ $Na, Si, Cl$
$(b)$ $Be, Mg, Ca$
Atomic mass of $Be = 9, Na = 23, Mg = 24, Si = 28, Cl = 35, Ca = 40$. Explain by giving reasons.

Define Newlands' law of Octaves.

What were the limitations of Dobereiner's classification?