How does the shielding effect of d-electrons compare to that of other electrons?

1. Weaker than s-electrons.
2. Stronger than s-electrons.  
3. Same as s-electrons.
4. Same as p-electrons.

Correct statement regarding transuranic elements is :

1. They have higher atomic number than uranium.

2. They are lighter than uranium.

3. They have lower atomic number than uranium.

4. They have same atomic number as uranium.

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

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

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

1. 13th  group

2. 15th group

3. 16 th group

4. 2nd group

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

The outer electronic configuration of Gd (Atomic no. 64) is:

1. 4f³ 5d⁵6d²

2. 4f⁸ 5d¹⁰6d²

3. 4f⁴ 5d⁴6d²

4. 4f⁷ 5d¹6s²