An element R forms the highest oxide R₂O₅. R belongs to:

1. 13th  group

2. 15th group

3. 16 th group

4. 2nd group

Amongst the following electronic configurations, the highest ionization energy
is represented by:

1. [Ne]3s²3p³

2. [Ne]3s²3p²

3. [Ar]3d¹⁰4s²4p³

4. [Ne]3s²3p¹

Which pair of elements is chemically most similar?

1. Na, Al

2. Cu, S

3. Ti, Zr

4. Zr, Hf

Lanthanoid contraction is caused due to :

1. the appreciable shielding on outer electrons by 4f electrons from the nuclear charge

2. the appreciable shielding on outer electrons by 5d electrons from the nuclear charge

3. the same effective nuclear charge from Ce to Lu

4. the imperfect shielding on outer electrons by 4f electrons from the nuclear charge

In the transition elements, the incoming electron occupies (n-1)d sublevel in preference to:

1. np

2. ns

3. (n-1)d

4. (n+1)s

The electronegativity of elements from group 1 to group 17 :

1. Decreases

2. Increases

3. Remains constant

4. All of the above

The electronic configuration of the most electropositive element is :

1. [He]2s¹

2. [Xe]6s¹

3. [He]2s²

4. [Xe]6s²

Which one of the following is an amphoteric oxide?

1. SO₂

2. B₂O₃

3. ZnO

4. Na₂O

Transition elements exhibit variable oxidation states because they release electrons from the following orbits:

1. ns and np orbits

2. (n-1)d and ns orbits

3. (n-1)d orbits

4. ns orbits

Elements of group IB  is called as: