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

 All the non-metals in the long form of the periodic table are placed under:

1. s-Block

2. p-Block

3. f-Block

4. d-Block

General electronic configuration of the transition elements is given by:

1. ns²nd^1-10

2. ns²np⁶nd^1-10

3. (n-1)d^1-10np⁶

4. (n-1)d^1-10ns^1-2

The statement that is incorrect for the periodic classification of elements is:

1. The properties of elements are a periodic function of their atomic number.

2. Non-metallic elements are lesser in number than metallic elements.

3. The first ionization energies of elements along a period do not vary in a regular manner with an increase in atomic number.

4. For transition elements, the d-subshells are filled with electrons monotonically with an increase in atomic number.

Which among the following options is a nonmetal?

The ions O^2-, F^-, Na⁺, Mg^2+, and Al³⁺ are isoelectronic. Their ionic radii show [2003]

1. an increase from O^2- to F^- and then decrease from Na⁺ to Al³⁺

2. a decrease from O^2- to F^- and then increase from Na⁺ to Al³⁺

3. a significant increase from O^2- to Al³⁺

4. a significant decrease from O^2- to Al³⁺

An example of metalloid elements in the periodic table is:

The element with atomic number 26 is:

1. A non-metal

2. Krypton

3. Iron

4. Manganese

The alkali metals have:

1. highest ionization energy

2. largest atomic radii

3. highest density

4. highest electronegativity

The telluric helix was given by:

1. Newland

2. Mendeleev

3. Lothar Meyer

4. De-chancourtois