Chemistry Test - 33

\(Q = i \times t\)

\(Q =10 \times 10^{-3} \times t\)

\(2 H_{2} O+2 e^{-} \rightarrow H_{2}+2 O H^{-}\)

To liberate \(0.01\) mole of \(H_{2}\), \(0.02\) Faraday charge is required

\(Q=0.02 \times 96500 C\)

\(\therefore 0.02 \times 96500=10^{-2} \times t\)

\(\Rightarrow t=19.3 \times 10^{4}\) sec

Molar mass of \({KI}=39+127=166 {~g} {~mol}^{-1}\)

\(20 \%\) aqueous solution of KI means \(20 {~g}\) of \({KI}\) is present in \(100 {~g}\) of solution.

Therefore,

Mass of \(KI=20 {~g}\)

That is,

\(20 {~g}\) of \({KI}\) is present in \((100-20) {g}\) of water \(=80 {~g}\) of water

We know that:

Molality of the solution \(=\frac{\text { Moles of } K I}{\text { Mass of water in } {kg}}\)

\(=\frac{\frac{\text {Mass of KI}}{\text {Molar Mass of KI}} }{\text { Mass of water in } {kg}}\)

\(=\frac{\frac{20}{166}}{0.08} {~m}\)

\(=1.506 {~m}\)

\(=1.51 {~m}\)

A poisonous gas is adsorbed at activated charcoal. The activated charcoal is adsorbent.

Adsorption is the adhesion of molecules of gas, liquid, or dissolved solid particles onto the surface. In this process a layer of the adsorbate the molecules or atoms being accumulated on the surface of the adsorbent.

The atomic number is equal tonumber of protons \(= 16\). The element issulphur (S).

Atomic mass number \(=\) number ofprotons \(+\) number of neutrons

\(= 16 + 16 = 32\)

Species is not neutral as the number ofprotons is not equal to electrons. It isanion (negatively charged) with chargeequal to excess electrons \(= 18 – 16 = 2\)

Thus symbol is \({ }_{16}^{32} \mathrm{~S}^{2-}\).

Maleic acid is stronger than fumaric acid.

• Maleic acid is cis-butenedioic acid whereas fumaric acid is trans-butenedioic acid.
• Maleic acid is able to lose \(H^{+}\)ion and it results in the formation of intra hydrogen bond. Whereas fumaric acid being a trans isomer has strong interaction with both the oxygen atoms of each carboxylic group. Therefore, fumaric acid is unable to give hydrogen ions as compared to maleic acid.
• That is why, maleic acid is stronger than fumaric acid.

Alkaline \(\mathrm{KMnO}_{4}\) is called Baeyer's reagent. Baeyer's reagent is an alkaline solution of cold potassium permanganate, which is a powerful oxidant making this a redox reaction. Reaction with double or triple bonds (\(-C=C-\) or \(-C \equiv C-)\) in an organic material causes the colour to fade from purplish-pink to brown. It is a syn addition reaction.

The melting and boiling points of alkali metals are quite low and they decrease down the group due to weakening of their metallic bonds. Francium is the only element in this group which is a liquid at room temperature.

The correct order of increasing acidic strength is Ethanol < Phenol < Acetic acid < Chloroacetic acid.

• Phenol is more acidic than ethanol because in phenol, the phenoxide ion obtained on deprotonation is stabilized by resonance which is not possible in case of ethanol.
• Also carboxylic acids are more acidic than alcohols and phenols as the carboxylate ion is stabilized by resonance. Chloroacetic acid is more acidic than acetic acid due to inductive effect of chlorine atom which stabilizes the carboxylate anion.

All the given options are correctly matched.

Aldehyde has \(C _{n} H _{2} O\) general formula. Example: Ethanal \(- C _{2} H _{4} O , n =2\)

Carboxylic acid has \(C _{n} H _{2 n} O _{2}\) general formula. Example: Propionic acid \(- C _{3} H _{6} O _{2}, n =3\)

Cycloalkane has \(C _{ n } H _{2 n }\) general formula. Example: Cyclobutane \(- C _{4} H _{8}, n =4\)

Alkane also has \(C _{n} H _{2 n +2}\) general formula. Example: Ethane \(- C _{2} H _{6}, n =2\)

Rayon:

• Rayon is asynthetic fibrewhose properties are similar to that ofsilk.
• Rayon is obtained from anatural source like wood pulp.
• It has a veryshiny appearanceand hence calledartificial silk.

​Teflon:

• Teflon is short for tetrafluoroethylene, also known asPTFE.
• It is used to make non-stick cookware, pans because it isunreactivein nature and hasnon-stick properties.
• It is a synthetic polymer.

Bakelite:

• Plasticis also a polymer likesynthetic fibre.
• There are two types of plastics:thermoplastics and thermosetting plastics.
• Thermosetting plasticsare the one which when moulded oncecannotbe softened by heating.

PVC:

• PVCstands for Poly Vinyl Chloride.
• It is a plastic that getsdeformed easilywhen heated and can be moulded again into other forms.
• It is used to makepipes, containers, various type of toys etc.