Chemistry Test-34

The troposphere is the lowest layer of the atmosphere. It extends 10 km above sea level. The outer surface of the troposphere is the tropopause. In this layer, temperature decreases with increasing altitude. Aviation-related activities take place in the troposphere.

The expression of energy is:

\(E=-\frac{K}{n^{2}} ;\) where \(K\) is constant

So, \(\Delta E=E_{n+1}-E_{n}=-K\left[\frac{1}{(n+1)^{2}}-\frac{1}{n^{2}}\right]=\frac{(2 n+1) K}{[n(n+1)]^{2}}\)

For \(n=1, \Delta E=\frac{3 K}{4}=0.75 K\)

\(n=2, \Delta E=\frac{5 K}{36}=0.14 K\)

\(n=3, \Delta E=\frac{7 K}{144}=0.049 K\)

Thus, in Bohr's theory of the atom, the energy difference between two successive energy levels decreases with an increase in the value of n.

Given: Weight of Urea \(=12 {~g}\)

And, weight of sucrose \(=68.4 {~g}\)

We know that: Number of moles \(=\frac{\text{Weight}}{\text{Molar mass}}\)

Therefore, Moles of urea \(=\frac{12}{60}=0.2\)

(Molar mass of Urea is \(60 {gm}\). )

Moles of sucrose \(=\frac{68.4}{342}=0.2\)

(Molar mass of sucrose is \(342 {gm}\))

Since, there are equal moles of solute in equal volumes of water, the mole fraction is the same. As per Raoult's law, the relative lowering of pressure will also be the same.

The rate of chemical change is directly proportional to product of active masses at that temperature. In fact, the rate of a reaction is defined as the change in concentration (number of moles per litre) of reactants or products per unit time

NADP is a coenzyme.

\(\overset{+1}{\mathrm{HBr}} \mathrm{Br} \longrightarrow \mathrm{Br}_{2}^{0}, E_{H B r O / B r_{2}}^{0}=1.595 \mathrm{~V}\)

\(\overset{+1}{\mathrm{HBr}} \mathrm{Br} \longrightarrow \overset{+5}{\mathrm{Br}}\mathrm{O}_{3}^{-}, E_{\mathrm{Br}\mathrm{O}_{3}^{-}/ H B r O}^{0}=1.5 \mathrm{~V}\)

\(E_{\text {cell }}^{\circ}\) for the disproportionation of \(\mathrm{HBrO}\),

\(E_{\text {cell }}^{\circ}=E_{H B r O / B_{2}}^{\circ}-E_{\mathrm{BrO}_{3}^{-} / \mathrm{HBr} \mathrm{O}}^{\circ}\)

= 1.595 − 1.5

= 0.095V = +ve

We know that\(\Delta\mathrm { H=\Delta U+\Delta n_{\mathrm{g}} R T }\),\(\Delta\mathrm { U=\Delta H-\Delta n_{\mathrm{g}} R T}\)
Given that \(\mathrm {R=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}, \Delta H=-163.14 \mathrm{~kJ} \mathrm{~mol}^{-1}}\),\(\mathrm {T=25+273=298 \mathrm{~K}, \Delta n_{\mathrm{g}}=3-2=1 \mathrm{~mol} }\).
For \(180 \mathrm{~g} \mathrm{~N}_2 \mathrm{O}\), first calculate the number of moles of \(\mathrm{N}_2 \mathrm{O}\) and then how many \(\mathrm{kJ}\) of energy will be released for that many moles of \(\mathrm{N}_2 \mathrm{O}\). Substituting the values, we have\(\Delta U =-163.14 \mathrm{~kJ}-(1 \mathrm{~mol})\left(8.314 \times 10^{-3} \mathrm{~kJ} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}\right)(298 \mathrm{~K}) \)\(=-165.62 \mathrm{~kJ}\)
Number of \(\mathrm{mol} \mathrm{~N}_2 \mathrm{O}=180 \mathrm{~g}\left(\frac{1 \mathrm{~mol} \mathrm{~N}{ }_2 \mathrm{O}}{44.02 \mathrm{~g} \mathrm{~N}_2 \mathrm{O}}\right)=4.09 \mathrm{~mol}\) \(\mathrm{N}_2 \mathrm{O}\)
Amount of energy released \( =4.09 \mathrm{~mol} \mathrm{~N}_2 \mathrm{O}\left(\frac{-165.62 \mathrm{~kJ}}{2 \mathrm{~mol} \mathrm{~N}_2 \mathrm{O}}\right) \)\(=-338 \mathrm{~kJ}\)

The most electropositive halogen is\(\mathrm{I}\) (Iodine).

The tendency of an element to lose electrons is known as electropositivity.As we go down a group, the electropositivity increases, so Iodine (\(\mathrm{I}\)) becomes the most electropositive element.Iodine has a tendency to lose electrons and form positive ions during chemical reactions.Iodine is the least reactive of the halogens as well as the most electropositive halogen.

The statement 'Buna-S stands for natural rubber ' is not correct.

• PVC stands for poly vinyl chloride.
• PTFE stands for poly tetrafluoro ethane or Teflon.
• PMMA stands for polymethyl methyl acrylate.
• Buna-S stands for butadiene and Styrene.

In I and IV, amine is not formed.

I. Hydrolysis of\(R C N ; R N C \rightarrow R C O O H+N H_{3}\)

II. Reduction of \(R C H=N O H\)

\(RCH=NOH \rightarrow RCH_{2} NH_{2}+H_{2} O\)

III. Hydrolysis of RNC

\(R N C+2 H_{2} O \stackrel{\Delta}{\rightarrow} R N H_{2}+H C O O H\)

IV. Hydrolysis of \(RCONH_{2}\)

\(RCONH_{2} \rightarrow {RCOOH}+{NH}_{3}\)