When K₂Cr₂O₇ is used in an acidic medium during titration, the oxidation number of Cr in the product side is-

1. +6
2. +2
3. +3
4. +4

The radius of La³⁺ (Atomic number of La =57) is 1.06 Å. Which one of the following given values will be closest to the radius of Lu³⁺ (Atomic number of Lu = 71)? 
1. 1.60 Å
2. 1.40 Å
3. 1.06 Å
4. 0.85 Å

Which of the following group of transition metals is called coinage metals ? 

1.  Cu , Ag, Au 

2. Ru , Rh, Pd 

3. Fe , Co , Ni 

4. Os , Ir , Pt 

Ce³⁺ , La³⁺ , Pm³⁺ and Yb³⁺  have ionic radii in the increasing order as: 

1. La³⁺ < Ce³⁺ < Pm³⁺ < Yb³⁺

2. Yb³⁺ < Pm³⁺ < Ce³⁺ < La³⁺

3. La³⁺ = Ce³⁺ < Pm³⁺ < Yb³⁺  

4. Yb³⁺ < Pm³⁺ < La³⁺ < Ce³⁺

The common oxidation states associated with cerium (Ce) are:

1. +3 , +4 

2. +2, +3 

3. +2, +4 

4. +3, +5