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:

Element that has the greatest tendency to lose an electron is :

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

1. 4f³ 5d⁵6d²

2. 4f⁸ 5d¹⁰6d²

3. 4f⁴ 5d⁴6d²

4. 4f⁷ 5d¹6s²

The radius of La³⁺ (at. no. 57) is 1.06 $\stackrel{°}{\mathrm{A}}$ The radius of Lu³⁺ (at.no. 71) might be:

1. 1.06  $\stackrel{°}{\mathrm{A}}$

2. 0.85  $\stackrel{°}{\mathrm{A}}$

3. 1.60  $\stackrel{°}{\mathrm{A}}$

4. 1.40  $\stackrel{°}{\mathrm{A}}$

Which of the following transition metal ions has the lowest density?

1. Copper

2. Nickel

3. Scandium

4. Zinc

Ionic radii are :

1. Inversely proportional to the effective nuclear charge.

2. Inversely proportional to the square of effective nuclear charge.

3. Directly proportional to the effective nuclear charge.

4. Directly proportional to the square of effective nuclear charge.

Which one is a metalloid?

1. Tin

2. Germanium

3. Sulphur

4. Carbon

Zn and Cd do not show variable valency like 'd' block elements due to :

1. Softness

2. Completed 'd' orbital

3. Two electrons in outermost orbit

4. Low m.p.