According to Moseley, a straight-line graph is obtained on plotting:

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

The telluric helix was given by:

1. Newland

2. Mendeleev

3. Lothar Meyer

4. De-chancourtois

What is the combining ratio of a number of elements in group l with elements in group 17th of the periodic table ?

1. 1 : 2

2. 1 : 3

3. 2 : 1

4. 1 : 1

An atom of the element A has 3 electrons in its outermost shell while another atom X has 6 electrons in its outermost shell. The formula of the compound between A and X could be.

1. A₂X₃

2. AX₃

3. A₃X₂

4. A₂X