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

If atomic number of an element of He-family is Z then which of the following atomic number will highest EA?

(1) Z - 2

(2) Z - 1

(3) Z + 1

(4) Z + 2

Which of the following statements is incorrect?

Consider the following statements:

(I) Rutherford name was associated with the development of periodic table.

(II) A metal M having electronic configuration $1s^2,<mspace\; width="1em"></mspace>2s^2,<mspace\; width="1em"></mspace>2p^6,<mspace\; width="1em"></mspace>3s^2,<mspace\; width="1em"></mspace>3p^6<mspace\; width="1em"></mspace>,3d^{10},<mspace\; width="1em"></mspace>4s^1$ is d-block element.

(III) Diamond is  an element.

(IV) The electronic configuration of the most electronegative elements is $1s^2,<mspace\; width="1em"></mspace>2s^2,<mspace\; width="1em"></mspace>2p^5,$ 

and select the correct one from the given codes.

(A) I, II, IV                                      (B) I, II, III, IV

(C) II, IV                                         (D) I, III, IV

There are four elements 'p', 'q', 'r' and 's' having atomic number Z-1, Z, Z+1 and Z+2 respectively. If there element 'q' is an inert gas, select the correct answers from the following statements.

(i) 'p' has most negative electron gain enthalpy in the respective period.

(ii) 'r' is an alkali metal.

(iii) 's' exists in +2 oxidation state.

(1) (i) and (ii)                     

(2) (ii) and (iii)

(3) (i) and (iii)                     

(4) (i), (ii) and (iii)

Assertion: The $5^{th}$ period of the periodic table contains 18 elements and not 32.

Reason: When n = 5, the value of l = 0, 1, 2, 3. The order in which the energy of available orbits 4d, 5s and 5p increases is 5s < 4d < 5p, and the total number of orbitals available is 9, thus 18 electrons can be accommodated.