MHT CET 2018 :: Chemistry :: General questions

• Chemistry - General questions

Identify the oxidation states of titanium (Z=22) and copper (Z=29) in their colourless compounds.

Answer:

Explanation:

 Electronic  configuration of titanium (Ti) (Z=22) is [Ar]₁₈  3d² 4s². In case of Ti4+, the electronic configuration will be [Ar]₁₈ 3d⁰ 4s⁰

Similarly , electronic configuration  of copper (Cu) (Z=29) is [Ar]₁₈ 3d¹⁰ 4s¹ . On loosing one electron it acquires stable electronic configuration , i.e [Ar]₁₈ 3d¹⁰

In both Ti⁴⁺ and Cu⁺ no unpaired electron is present as a result, no d-d transition occurs and therefore these are colourless in nature.

 Which among the group 15 elements does not exist as tetra atomic molecule?

Answer:

Explanation:

Nitrogen due to smaller size, high ionisation energy high electronegativity and the absence of d-oribtal does not exist as a tetra atomic molecule. Nitrogen cannot form d$\pi$-p$\pi$  bond due to absence of d-orbital, so it cannot expand its covalency beyond four as the heavier members of this group can.

The correct relation between elevation of boiling point and molar mass of solute is 

Answer:

Explanation:

 For dilute solutions, the elevation  is boiling point is directly proportional to the molal concentration  pf the solute in solution (m) 

 Thus,  $\triangle T_{b}\propto m$

 $\triangle T_{b}= k_{b}m$

 where, k_b is molal boiling point elevation constant

As, molality (m)= Moles of solute(n₂) / Mass of solvent (W₁)(in kg)

 Moles of solute $(n_{2})= \frac{W_{2}}{M_{2}}$

$\therefore$   $\triangle T_{b}= \frac{k_{b}\times W_{2}}{M_{2}\times W_{1}}$

$\Rightarrow$    $ M_{2}= \frac{k_{b}. W_{2}}{\triangle T_{b}. W_{1}}$

 The element  that does not exhibit allotropy is 

Answer:

Explanation:

All the members of group 15 (except bismuth) shows the property of allotropy.Nitrogen exists in two solid allotropic forms. Phosphorus exists in several allotropic forms . Arsenic and antimony exists in three allotropic forms

 Which of the following is not a tranquilliser?

Answer:

Explanation:

 Bromopheniramine is not  a tranquiliser.It is an antihistamine while meprobamate, Equanil, chlordiazepoxide are examples of tranquiliser. Tranquilisers are neurologically active drugs and used for the treatment of stress, fatigue anxiety and mild or even severe mental diseases.

• Chemistry - General questions