Chemistry Test-4

When benzoic acid is treated with PCl₅, benzoyl chloride is obtained, including POCl₃ and HCl as a side product.

Replacing OH by Cl, we get benzoyl chloride.

Here, the correct option is (A).

An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. Therefore liquid state is right.

The unbalanced redox reaction is,

\(\mathrm{MnO}_{4}^{-}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-}+\mathrm{H}^{+} \rightarrow \mathrm{Mn}^{2+}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}\)

Balance C atoms,

\(\mathrm{MnO}_{4}^{-}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-}+\mathrm{H}^{+} \rightarrow \mathrm{Mn}^{2+}+2 \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}\)

The oxidation number of \(\mathrm{Mn}\) decreases from \(+7\) to \(+2\).

The decrease in the oxidation number is \(7-2=5\)

The oxidation number of \(C\) increases from \(+3\) to \(+4\).

The increase in the oxidation number for \(1 \mathrm{C}\) atom is \(4-3=1\)

The increase in the oxidation number for \(2 C\) atom is \(2 \times 1=2\)

To balance the increase in the oxidation number with decrease in the oxidation number, multiply Mn containing species with 2 and C containing species with 5.

\(2 \mathrm{MnO}_{4}^{-}+5 \mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow 2 \mathrm{Mn}^{2+}+10 \mathrm{CO}_{2}\)

Balance \(\mathrm{H}\) atoms by adding \(16 \mathrm{H}^{+}\)ions to the reactants side.

\(2 \mathrm{MnO}_{4}^{-}+5 \mathrm{C}_{2} \mathrm{O}_{4}^{2-}+16 \mathrm{H}^{+} \rightarrow 2 \mathrm{Mn}^{2+}+10 \mathrm{CO}_{2}+8 \mathrm{H}_{2} \mathrm{O}\)

This is the balanced equation.

The dispersion medium may be a gas, a liquid, or a solid and the dispersed phase may also be any of these, with the exception of one gas in another. A system of liquid or solid particles colloidally dispersed in a gas is called an aerosol.

It has two lone pairs of electrons on oxygen atom Carbon atom in it is sp hybridized In forming metal carbonyls, oxygen is attached to the metal atom It has a large value of diple moment.

\(CO\) has the strucuture : which involves sp hybridisation of \({C}\) -atom . Because of donation of electron by \(O\)-atom to \(C\)-atom, it has low polar character and hence low dipole moment \(\left(0.39 C \frac{m}{0.117} D\right)\).

Covalency of \(\mathrm{N}\) in \(\mathrm{N}_{2} \mathrm{O}_{5}\) is 4. Covalency is valence characterized by the sharing of electrons in a chemical compound. The covalency of nitrogen in dinitrogen pentoxide is 4 because 3 are covalent bonds and one is a coordinate covalent bond.

The atomic number of chromium = 24

• The electron configuration for Chromium the first two electrons will go in the 1s orbital.
• Since 1s can only hold two electrons the next 2 electrons for Chromium go in the 2s orbital. The next six electrons will go in the 2p orbital.
• The p orbital can hold up to six electrons.
• The next two electrons in the 3s.
• Later the next six electrons.
• Now shift to the 4s orbital where we place the remaining two electrons.
• The remaining electrons move in the 3d orbital.
  Expected Electronic configuration
  Therefore, the expected electron configuration for Chromium will be [Cr]3s²3p⁶3d⁵4s¹
  

Mercury in its +1 form is most toxic.The toxic effects of mercury depend on its chemical form and the route of exposure. Methylmercury [CH₃Hg] is the most toxic form. It affects the immune system, alters genetic and enzyme systems, and damages the nervous system, including coordination and the senses of touch, taste, and sight.

Writing the reaction for carbonic acid, we get:

\(\mathrm{H}_{2} \mathrm{CO}_{3} \rightleftharpoons \mathrm{H}^{+}+\mathrm{HCO}_{3}^{-} ; \mathrm{K}_{1}=4.2 \times 10^{-7}\)

\(\mathrm{HCO}_{3} \rightleftharpoons \mathrm{H}^{+}+\mathrm{CO}_{3}^{2-} ; \mathrm{K}_{2}=4.8 \times 10^{-11}\)

\(\mathrm{K}_{1} \gg\mathrm{K}_{2}\),

So, \(\mathrm{H}_{2} \mathrm{CO}_{3}\) ionises more than \(\mathrm{HCO}_{3}^{-}\) and hence, contribution of \(\mathrm{H}^{*}\) is mostly due to ionisation of carbonic acid, thus, the concentration of \(\mathrm{H}^{+}\) and \(\mathrm{HCO}_{3}^{-}\) are approximately equal.

The screening effect of \(d\) - electrons is less than \(\mathrm{p}\) - electrons. In general, \(\mathrm{d}\) and \(\mathrm{f}\) electrons have a poor shielding effect compared to \(\mathrm{s}\) and \(p\) electrons. This is because \(s\) and \(p\) electrons are close to the nucleus whereas \(d\) and \(f\) electrons are more diffused (away from the nucleus).

The number of atoms of the ligand that are directly bound to the central metal atom or ion by coordinate bonds is known as the coordination number of the metal atom or ion.

The coordination number of metal=number of σσ⁡ bonds formed by metal with ligands.

[Cu(NH3)4]2+ : Tetrahedral complex i.e., C.N. = 4

[Fe2+(CN)6]-4 : Octahedral complex C.N. = 6

We know,
Lattice Energy \(\propto \frac{q_{1} q_{2}}{r_{c}+r_{2}}\) where \(q=\) charge of the ion, \(r=\) distance between two ions.
Lattice energy is defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. It is directly proportional to the charge on the ions and inversely proportional to the size of the ions.