Board Paper of Class 12-Science 2014 Chemistry (SET 2) - Solutions

State Henry's Law. What is the effect of temperature on the solubility of a gas in a liquid? VIEW SOLUTION

Define the following terms:

(i) Pseudo first-order reaction
(ii) Half-life period of reaction (t_1/2). VIEW SOLUTION

Write the principle behind the following methods of refining:

(i) Hydraulic washing
(ii) Vapour-phase refining VIEW SOLUTION

Draw the structure of major monohalo product in each of the following reactions :

(i)

(ii) VIEW SOLUTION

(i) Which alkyl halide from the following pair is chiral and undergoes faster S_N2 reaction?


(ii) Out of S_N1 and S_N2, which reaction occurs with

(a) Inversion of configuration
(b) Racemisation VIEW SOLUTION

Complete the following chemical equations :
(i) Ca₃P₂ + H₂O →
(ii) Cu + H₂SO₄(conc.) → Arrange the following in the order of the property indicated against each set :
(i) HF, HCl, HBr, HI − increasing bond-dissociation enthalpy.
(ii) H₂O, H₂S, H₂Se, H₂Te − increasing acidic character. VIEW SOLUTION

Write the IUPAC name of the complex [Cr(NH₃)₄Cl₂]⁺. What type of isomerism does it exhibit? VIEW SOLUTION

An element with density 11.2 g cm^–3 forms a f.c.c. lattice with edge length of 4 × 10^–8 cm.
Calculate the atomic mass of the element.
(Given : N_A = 6.022 × 10²³ mol^–1) VIEW SOLUTION

Examine the given defective crystal:



Answer the following questions :
(i) What type of stoichiometric defect is shown by the crystal?
(ii) How is the density of the crystal affected by this defect?
(iii) What type of ionic substances show such defect? VIEW SOLUTION

Calculate the mass of a compound (molar mass = 256 g mol⁻¹) to be dissolved in 75 g of benzene to lower its freezing point by 0.48 K (K_f = 5.12 K kg mol⁻¹). VIEW SOLUTION

Give the structures of A, B and C in the following reactions :

(i)

(ii)
 
How will you convert the following?
(i) Nitrobenzene into aniline

(ii) Ethanoic acid into methanamine

(iii) Aniline into N−phenylethanamide

(Write the chemical equations involved.) VIEW SOLUTION

(a) Write the mechanism of the following reaction :
(b) Write the equation involved in Reimer-Tiemann reaction. VIEW SOLUTION

After the ban on plastic bags, students of a school decided to make people aware of the harmful effects of plastic bags on the environment and Yamuna River. To make the awareness more impactful, they organised a rally by partnering with other schools and distributed paper bags to vegetable vendors, shopkeepers and departmental stores. All the students pledged not to use polythene bags in the future to save the Yamuna River.

After reading the above passage, answer the following questions:
(i) What values are shown by the students?
(ii) What are bio-degradable polymers? Give one example.
(iii) Is polythene a condensation or an addition polymer? VIEW SOLUTION

(a) Draw the structures of the following:

(i) XeF₂
(ii) BrF₃

(b) Write the structural difference between white phosphorus and red phosphorus. VIEW SOLUTION

(a) In reference to Freundlich adsorption isotherm, write the expression for adsorption of gases on solids in the form of an equation.
(b) Write an important characteristic of lyophilic sols.
(c) Based on the type of particles of dispersed phase, give one example each of associated colloid and multimolecular colloid. VIEW SOLUTION

Account for the following :

(i) Bi(V) is a stronger oxidizing agent than Sb(V).
(ii) N − N single bond is weaker than P − P single bond.
(ii) Noble gases have very low boiling points. VIEW SOLUTION

(i) Name sweetening agent used in the preparation of sweets for a diabetic patient.

(ii) What are antibiotics? Give an example.

(iii) Give two examples of macromolecules that are chosen as drug targets. VIEW SOLUTION

The following data were obtained during the first-order thermal decomposition of SO₂Cl₂ at a constant volume:
SO₂Cl₂(g) → SO₂(g) + Cl₂(g)

Experiment	Time/s−1	Total pressure/atm
1 2	0 100	0.4 0.7

Calculate the rate constant.
(Given : log 4 = 0.6021, log 2 = 0.3010) VIEW SOLUTION

(i) Deficiency of which vitamin causes rickets?
(ii) Give an example each for fibrous protein and globular protein.
(iii) Write the product formed on reaction of D-glucose with Br₂ water. VIEW SOLUTION

(a) Write the products of the following reactions:
     (i)
     (ii) 
     (iii)
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
     (i) Benzaldehyde and Benzoic acid
     (ii) Propanal and Propanone
(a) Account for the following:
     (i) CH₃CHO is more reactive than CH₃COCH₃ towards reaction with HCN.
     (ii) Carboxylic acid is a stronger acid than phenol.
(b) Write the chemical equations to illustrate the following name reactions:
     (i) Wolff-Kishner reduction
     (ii) Aldol condensation
     (iii) Cannizzaro reaction VIEW SOLUTION

(a) Define the following terms :

(i) Limiting molar conductivity
(ii) Fuel cell

(b) Resistance of a conductivity cell filled with 0.1 mol L⁻¹ KCl solution is 100 Ω. If the resistance of the same cell when filled with 0.02 mol L⁻¹ KCl solution is 520 Ω, calculate the conductivity and molar conductivity of 0.02 mol L⁻¹ KCl solution. The conductivity of 0.1 mol L⁻¹ KCl solution is 1.29 × 10⁻² Ω⁻¹ cm⁻¹.
 
(a) State Faraday's first law of electrolysis. How much charge in terms of Faraday is required for the reduction of 1 mol of Cu²⁺ to Cu.

(b) Calculate emf of the following cell at 298 K:
Mg(s) | Mg²⁺(0.1 M) || Cu²⁺ (0.01) | Cu(s)
[Given E^o_cell = +2.71 V, 1 F = 96500 C mol^–1] VIEW SOLUTION

(a) How do you prepare:
(i) K₂MnO₄ from MnO₂?
(ii) Na₂Cr₂O₇ from Na₂CrO₄?

(b) Account for the following:
(i) Mn²⁺ is more stable than Fe²⁺ towards oxidation to +3 state.
(ii) The enthalpy of atomisation is lowest for Zn in 3d series of the transition elements.
(iii) Actinoid elements show wide range of oxidation states.
 
(i) Name the elements of 3d transition series that show maximum number of oxidation states. Why does this happen?
(ii) Which transition metal of 3d series has positive E° (M²⁺/M) value and why?
(iii) Out of Cr³⁺ and Mn³⁺, which is a stronger oxidising agent and why?
(iv) Name a member of the lanthanoid series that is well-known to exhibit +2 oxidation state.
(v) Complete the following equation:
${\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-} \to$ VIEW SOLUTION