Important Questions for CSIR NET Chemical Science - INORGANIC CHEMISTRY- PART III

Most Important Questions on Inorganic Chemistry - Part III (Download PDF)

1. Statement: The ore of aluminium is alumina (Al₂O₃) which has oxygen and not sulfur bonded to aluminium. What is the possible reason for the above statement?

1. Al³⁺ is hard acid and O^2- is hard base.
2. Al³⁺ is soft acid and O^2- is hard base.
3. Al³⁺ is hard acid and O^2- is soft base.
4. Al³⁺ is soft acid and O_2- is soft base.

2. How many molybdenum atom/atoms is/are present in Xanthine oxidase enzymes?

1. 1
2. 2
3. 3
4. 4

3. How many molecular orbitals can be constructed from the valence shell orbitals of the constituent atoms in CH4?

1. 3
2. 6
3. 4
4. 8

4. Using the periodic table only, rank the elements in each of the following correct sets in order of decreasing IE1.

1. Kr > He > Ar
2. Sb < Te < Sn
3. Ca > K > Rb
4. I < Xe > Cs

5. The light pink colour of [Co (NH3)6]+2 and dark blue colour of [Co(OH)6]-4 is due to :

1. MLCT transition in first and d-d transition in second.
2. MLCT transition in both.
3. d-d Transition in both.
4. d-d transition in first and LMCT in second.

6. Which of the following Ligands will form a stable complex with Ln3+ ion?

1. H₂O
2. CO
3. C₂H₄
4. PPh₃

7. What will be the total numbers of fine and hyperfine EPR lines for octahedral high-spin Mn (II) complexes respectively (I = 5/2 for Mn)?

1. 5 and 30
2. 5 and 33
3. 3 and 30
4. 3 and 33

8. In an equimolar ratio at 120-150ºC with the help of appropriate solvents, triphosphazene is prepared by reacting X and Y. Identify reactants X and Y, respectively.

1. PCl5; NH3
2. PCl3; NH3
3. PCl3; NH4Cl
4. PCl5; NH4Cl

9. Hapticity of S in Fe3S4 is:

1. 1
2. 2
3. 3
4. 4

10. The main ingredient of gunpowder:

1. Cu, Sn and Zn
2. Cu and Fe
3. Mn and Tc
4. Zn and Cd

SOLUTIONS

Solution 1. HSAB principle: According to this principle, Hard acid tends to react with hard base while the soft acid tends to bond with soft base. As Al3+ belongs to the hard acid category, it tends to bond with the hard base. Oxygen is a harder base compared to sulfur so, in nature, the ore of aluminum is Al2O3 as in accordance with HSAB principle.

Solution 2. Xanthine oxidase enzymes carry out the oxidation of xanthine to uric acid. It has two molybdenum atoms, four Fe2S2 and FAD (Flavin Adenine Dinucleotide) molecules. Each molybdenum atom is surrounded by one oxygen and three S atoms.

Solution 3. There are four atomic orbitals- one s and three p, in the valence shell of carbon, while each of the four hydrogen atoms possesses one orbital in its valence shell. So, there will be a total of eight atomic orbitals and eight molecular orbitals.

Solution 4. He > Ar > Kr: Group 8(A)(18) – IE decreases down a group

Te > Sb > Sn: Period 5 elements – IE increases across a group

Ca > K > Rb: Ca is to the right of K; Rb is below K

Xe > I > Cs: I is to the left of Xe; Cs is further to the left and down one period.

IE decreases as you proceed up in a group; IE increases as you go across a period.

Solution 5. In [Co (NH3)6] +2 and in [Co(OH)6]-4 , Co is in +2 oxidation state . Its configuration will be [Ar]3d74s0. Its d orbital configuration will be t2g5 eg2. It does not have a completely vacant orbital to accept electron pairs. In the first complex, NH3 is a sigma donor ligand only, so it will form one coordinate bond only. While in the second complex, OH- is a sigma donor and pi donor both but Co+2 does not have vacant space to accept a pair of electrons. So, there is no chance of MLCT and LMCT, still these complexes are coloured, due to d - d transition only.

Solution 6. Since the 4f orbitals are deeply buried the Lanthanides do not take part in Π bonding and are poor-Π donors. Therefore, the Π-acceptor Ligands like CO, PPh3 etc. do not form stable complexes with them.

Solution 7. The total no. of fine and hyperfine lines from high spin Mn (II) complex,

Number of fine lines

= No. of unpaired e- s in Mn = 5

No of hyperfine lines

= No. of unpaired e- s × (2nl + 1)

= 5 × 6

= 30

5 and 30

Solution 8. Polyphosphazenes contain more than two -P=N- groups. The preparation of triphenylphosphine can be represented as follows:
PCl5+NH4Cl→[NPCl2]3
The above reaction takes place in the presence of a halo hydrocarbon solvent at a temperature range of 120-150ºC.

Solution 9. Hapticity is defined as no. of donor atoms of the given ligands attached to the metal in a contiguous manner.

In this structure, only one atom of the ligand that is S is attached to metal only. So, the hapticity of S in Fe3S4 is 1.

Solution 10. Gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds.

Answer Key:

1. A
2. B
3. D
4. C
5. C
6. A
7. A
8. D
9. A
10. A

Download Important Questions On Inorganic Chemistry - Part III - Download PDF Here

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• Study Notes for CSIR NET Life Science - (Download PDF)
• Study Notes for CSIR NET Chemical Science - Download PDF Here!

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