The correct  sequence of increasing order of density is:

1. Li < K< Na < Rb < Cs

2. Li < Na < K < Rb < Cs

3. Cs < Rb < K < Na < Li

4. K < Li < Na < Rb < Cs

General electronic configuration of outermost and penultimate shell of an atom is
(n - 1)s² (n - 1) p⁶ (n - 1)d^x ns². If n = 4 and x = 5, the number of proton in the nucleus is:

1. > 25

2. < 24

3. 25

4. 30

The maximum number of valence electrons possible for atoms in the second period of the periodic table is:

1. 18

2. 10

3. 8

4. 2

The element having atomic number 19, is:

1. an inert gas

2. a metal with oxidation number +1

3. a non-metal with oxidation number -3

4. a metal with oxidation number -3

Which of the following has the least density?

1. Na

2. Li

3. Mg

4. K

Eka aluminium and Eka silicon are now known as:

An element having the electronic configuration of its atom ns² np² should have similar properties to those of:

1. Sodium

2. Carbon

3. Magnesium

4. Oxygen

The order of basic character of given oxides is:

1. Na₂O > MgO > Al₂O₃ > CuO

2. MgO > Al₂O₃ > CuO > Na₂O

3. Al₂O₃ > MgO > CuO > Na₂O

4. CuO > Na₂O > MgO > Al₂O₃

A variable oxidation state is shown by which of the following?

The lightest metal in the periodic table is:

1. H

2. Mg

3. Ca

4. Li