Chemistry Test-22

Boric acid used in talcum powder serves as an antiseptic.

Boric acid is added to talcum powder which is used for babies because it is a mild antiseptic and inhibits microbial growth. Chlorine is a disinfectant and it kills the micro-organisms and control algal growth in swimming pool's water.

In medicine, it has been used as a disinfectant and is a constituent of baby powders, antiseptics, diaper rash ointments, eye washes, gargles, and a variety of other consumer products for its mild antiseptic property.

\(\mathrm{N i}^{2+}\) ion has \(3 \mathrm{~d}^{8}\) outer electronic configuration. It undergoes \(\mathrm{dsp}^{2}\) hybridisation to form \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\) complex in which all the electrons are paired. Thus, it is diamagnetic.

The complex ion \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\) is square planar and diamagnetic.

For a dilute solution, Raoult's law states that:

The relative lowering of vapour pressure is equal to the mole fraction of solute.

Mathematically, it can be represented as \(\frac{\mathrm{P}^{\circ}-\mathrm{P}}{\mathrm{P}^{\circ}}=\mathrm{X}_{\mathrm{B}}\)

Here, \(\mathrm{P}^{\circ}\) is the pressure of pure solvent, \(\mathrm{P}\) is the partial pressure of solution and \(\mathrm{X}_{\mathrm{B}}\) is the mole fraction of solute.

An efflorescent salt is one that loses \(H _{2} O\) to atmosphere. For the reaction

\(CuSO _{4} \cdot 5 H _{2} O ( s ) \rightleftharpoons CuSO S _{4} \cdot 3 H _{2} O ( s )+2 H _{2} O _{(I)}\)

\(K_{P}=\left(P_{ H _{2} O }\right)^{2}=1.086 \times 10^{-4}\)

\(P_{ H _{2} O }^{\prime}=1.042 \times 10^{-2} atm =7.92 mm\)

\(\because \operatorname{If} P_{ H _{2} O }^{\prime}\) at \(25^{\circ} C <7.92 mm\) only, then reaction will proceed in forward direction.

Nylon 66 is a condensation polymer of hexamethylenediamine and adipic acid.

In an alkaline medium, the reduction of KMnO₄ with KI will takes place as

2KMnO₄ + H₂O → 2KOH + 2MnO₂

KI + 3[O] → KIO₃

Hence the overall reaction is

KI + 2KMnO₄ + H₂O → KIO₃ + 2KOH + 2MnO₂

So, one mole of KI will reduce two moles of KMnO₄

Given: Enthalpy of vaporisation of a substance is: \(8400{~J} {~mol}^{-1}\)

Temperature or boiling point of substance is: \(-173.15^{\circ}{C}\) 

We have Kelvin temperature\(=\) Celsius temperature+\(273.15^{\circ}{C}\)

\(=-173.15^{\circ}{C}+273.15^{\circ}{C}\)
\(=100{~K}\)

Change in entropy, \(\Delta S=\frac{q_rev}{T}\)

\(=\left(\frac{8400}{100}\right)\) \(=84~J m o l^{-1} K^{-1}\)                             

The elements occupying left and right side groups of periodic table are called representative elements.

The elements of group \(1\) and group \(2\) and the elements from group \(13\) to group \(18\) of the periodic table are known as representative elements. In other words, \(s\)-block and \(p\)-block elements are collectively known as representative elements.

Only ethyl accetate undergoes reduction with \(\mathrm{LiAlH}_{4}\) to give only alcohol, other esters given in option on reduction gives a mixture of alcohols.

\(\mathrm{CH}_{3} \mathrm{COOCH}_{2} \mathrm{CH}_{3}+2 \mathrm{H}_{2} \underset{\mathrm{LiAlH}_{4}}{\stackrel{\text { ether }}{\longrightarrow}} 2 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\).

1,3,5 -Triazine- 2,4,6 -triamine is the chemical name for melamine.