Chemistry Test - 8

According to kohlrausch law of independent migration of ions, the molar conductivity of an electrolyte at infinite dilution is equal to the sum of the contributions of the molar conductivites of its ions.

Hence,

\(\Lambda_{e q}^{\infty}\left(N H_{4} O H\right)=\Lambda_{e q}^{\infty}\left(N H_{4} C l\right)+\Lambda_{e q}^{\infty}(N a O H)-\Lambda_{e q}^{\infty}(N a C l)\)

Substitute values in the above equation \(\Lambda_{e q}^{\infty}\left(N H_{4} O H\right)=128.0+217.8-109.9\)

\(=235.9 \quad\) oh \(m^{-1} \mathrm{cm}^{2} e q^{-1}\)

The degree of dissociation is the ratio of the equivalent conductance at given concentration to the equivalent conductance at zero concentration. Hence, \(\alpha=\frac{\Lambda_{e q}}{\Lambda_{e q}^{\infty}}=\frac{9.30}{235.9}=0.04\)

Hence option A is the correct answer.

The mixture given in option (4) contains a weak acid (CH₃COOH) and its salt with strong base NaOH i.e. CH₃COONa.

It will form a perfect acidic buffer.

Hence, only option (4) is correct.

The oxidation number of chromium in \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\) is +6 and it reduces to +3 in \(\mathrm{Cr}^{3+}\). On balancing the equation, we will see 2 moles of chromium ion goes from +6 to +3 . Hence, there are 6 electrons involved in the above redox reaction.

Hence option D is the correct answer.

The expression for density \((d)\) is given below \(d=\frac{n M}{V N_{A}} \Rightarrow 8.27=\frac{4 \times 128}{a^{3} N_{A}} \Rightarrow a=4.68 \dot{A}\)

Here, \(n\) is the number of atoms per unit cell, \(M\) is the molecular mass, \(a\) is the edge length and \(N_{a}\) is Avogadro's number. So, the edge length of unit cell is 4.68 A However, for NaCl type structure \(r^{+}+r^{-}=\frac{a}{2} \Rightarrow r^{+}=\frac{4.68}{2}-1.24=1.1 \dot{A}\)

Hence option B is the correct answer.

2 centre-2 electron bonds are 4

Only four of these bonds are in the same plane.

Hence, option (1) is correct.

Bond angle \(H t B H t>H b B H b\)

Hence, option ( 2 ) is correct

In borax, \(B_{4} 0_{5}(O H)_{4}\), the number of B-O-B units is 5

Hence, option (3) is correct.

However, borozine is a planar structure, hence option (4) is incorrect.

Carbon tetrachloride can cause liver cancer and kidney damage.

Hence option B is the correct answer.

\(\left[\mathrm{Cr}(\mathrm{SCN})_{2}\left(\mathrm{NH}_{3}\right)_{4}\right]^{+}\) gives maximum number of isomers. These includes cis trans isomers and linkage isomers. In cis isomer, two SCN ligands are adjacent and in trans isomers, they are opposite. Linkage isomerism is due to ambidentate nature of the ligand SCN as it can coordinate either through S or through \(N\).

Hence option D is the correct answer.

\(S O_{3}(g) \rightleftharpoons S O_{2}(g)++\frac{1}{2} O_{2}(g)\)

\(n\) at Eq. \((0.1-x) \times \frac{x}{2}\)

\(\cup \operatorname{sing} P M=d R T\)

\(x=0.05\) and \(n_{T}=0.125\)

\(\chi_{S O_{3}}=\frac{0.05}{0.125}=0.4\)

\(\chi_{S O_{2}}=\frac{0.05}{0.125}=0.4\)

\(\chi_{O_{2}}=\frac{0.025}{0.125}=0.2\)

\(K_{P}=\frac{0.4 \times \times 0.2}{0.4}(1.6)^{\frac{1}{2}}=0.2529 a t m^{\frac{1}{2}}\)

Hence, option (2) is correct. Statement (4) is incorrect because at equilibrium, \(Q=K_{e q}\) and \(\Delta G=0\)

Hence option B is correct answer.

Sucrose is made up of two monomers \(\alpha\) -D-Glucose and \(\beta\) -D-Fructose. Cellulose is made up of \(\beta\) -D-Glucose. Starch is made up of \(\alpha\) -D-Glucose. Lactose is made up of two monomers \(\beta\) -D-Galactose and \(\beta\) -D-Glucose.

Hence option C is the correct answer.

Hence option D is the correct answer.

(1) Replacement of -OH by a halogen in an alcohol is nucleophilic substitution reaction. It is the protonted alcohol which acts as a substrate.

(2) Alcohols are acidic enough to react with active metals to liberate hydrogen gas. They are basic enough to accept a proton from strong acids.

(3) Secondary alcohols, on oxidation, give a ketone containing the same number of carbon atoms. Further oxidation will give carboxylic acid containing lesser number of carbon atoms.

(4) Primary alcohols, on oxidation, give an aldehyde containing the same number of carbon atoms. Further oxidation will give carboxylic acid containing the same number of carbon atoms.

Hence, only option (A) is incorrect.

0.2 moles of \(H N O_{3}\) will be neutralized with 0.2 moles of KOH. 0.3 moles of \(H N O_{3}\) will remain unneutralized. The heat of neutralisation of a strong acid and a strong alkali is \(57.0 \mathrm{kJ} / \mathrm{mol}\). When 0.2 moles of \(H N O_{3}\) is neutralized with 0.2 moles of \(\mathrm{KOH}\), the heat of neutralisation is \(0.2 \mathrm{mol} \times 57.0 \mathrm{kJ} / \mathrm{mol}=11.4 \mathrm{kJ}\)

Hence option B is the correct answer.

Dacron has an ester linkage. Condensation of diacid with dialcohol leads to an ester linkage.

Hence option B is the correct answer.

Salts of sorbic acid are used as preservative in cheese, baked food, pickles and meat.

Hence option B is the correct answer.

Option (C) is correct. I.U.P.A.C name for \(\left[C u\left(N H_{3}\right)_{4}\right]\left[P t C l_{4}\right]\) complex is tetraamminecopper(II) tetrachloridoplatinate (II). \(N H_{3}\) is neutral, making the first complex positively charged overall, so cobalt is in +2 oxidation state. \(C l\) has a- 1 charge, making the second complex the anion. As the charge on platinum is - 2 so the name ends with -ate followed by the charge in roman letters.