Chemistry (Theory) Official 2019-2020 ISC (Science) ISC Class 12 Question Paper Solution

Fill in the blanks by choosing the appropriate word/words from those given in the brackets:

(iodoform, volume, mass, haloform, gram equivalent, chloroform, carbylamine, sp³d², high, coke, d²sp³, low, gram mole, carbon monoxide)

Equivalent conductivity is the conducting power of all the ions furnished by one ______ of an electrolyte present in a definite ______ of the solution.

Fill in the blanks by choosing the appropriate word/words from those given in the brackets:

(iodoform, volume, mass, haloform, gram equivalent, chloroform, carbylamine, sp³d², high, coke, d²sp³, low, gram mole, carbon monoxide)

Bleaching powder, on treatment with ethanol or acetone gives ______. This is an example of ______ reaction.

Fill in the blanks by choosing the appropriate word/words from those given in the brackets:

(iodoform, volume, mass, haloform, gram equivalent, chloroform, carbylamine, sp³d², high, coke, d²sp³, low, gram mole, carbon monoxide)

Outer orbital complexes involve ______ hybridization and are ______ spin complexes.

Fill in the blanks by choosing the appropriate word/words from those given in the brackets:

(iodoform, volume, mass, haloform, gram equivalent, chloroform, carbylamine, sp³d², high, coke, d²sp³, low, gram mole, carbon monoxide)

Zinc oxide is reduced by ______ at 1673 K to form zinc and ______.

The packing efficiency of simple cubic structure, body centred cubic structure and face-centred cubic structure respectively is ______.

52.4%, 74%, 68%

74%, 68%, 52.4%

52.4%, 68%, 74%

68%, 74%, 52.4%

When acetone is treated with Grignard’s reagent, followed by hydrolysis, the product formed is ______.

Secondary alcohol

Tertiary alcohol

Primary alcohol

Aldehyde

Which of the following electrolytes is least effective in causing the flocculation of positively charged ferric hydroxide sol?

K₃[Fe(CN)₆]

K₂CrO₄

K₄[Fe(CN)₆]

KBr

On heating an aliphatic primary amine with chloroform and alcoholic potassium hydroxide, the organic compound formed is an ______.

Alkyl isocyanide

Alkanol

Alkanal

Alkyl cyanide

Match the following:

What is the common name of the polymer obtained by the polymerization of caprolactam? Is it an addition polymer or condensation polymer? 

Why Zn²⁺ ions are colourless while Ni²⁺ ions are green and Cu²⁺ ions are blue in colour?

Calculate the molar conductivity at infinite dilution for CH₃COOH if the molar conductivity at infinite dilution for NaCl, HCl and CH₃COONa are 126.45, 426.16 and 91.0 ohm⁻¹ cm² mol⁻¹ respectively.

Identify the compounds A, B, C and D.

\[\ce{C6H5COOH ->[SOCl2] A ->[NH3] B ->[Br2/KOH] C ->[NaNO2 + HCl][0-5^\circ C] D}\]

An element has atomic mass 93 g mol⁻¹ and density 11.5 g cm^–3. If the edge length of its unit cell is 300 pm, identify the type of unit cell. (N_A = 6.023 × 10²³ mol⁻¹)

Calculate the radius of copper atom. The atomic weight of copper is 63.55 g mol⁻¹. It crystallises in face-centred cubic lattice and has density of 8.93 g cm⁻³ at 298 K.

(N_A = 6.023 × 10²³ mol⁻¹)

Complete and balance the following chemical equation:

\[\ce{P4 + NaOH + H2O ->[Heat][Inert atm.]}\] ______ + ______

Complete and balance the following chemical equation:

\[\ce{Cu + \underset{dil.}{HNO3} ->}\] ______ + ______ + ______

Write the chemical equation for the reaction of glucose with bromine water.

Write the zwitter ion structure of glycine.

How do antiseptics differ from disinfectants?

Name a substance which can be used as an antiseptic as well as disinfectant.

An alloy of gold (Au) and cadmium (Cd) crystallises with a cubic structure in which gold atoms occupy the corners and cadmium atoms fit into the face centres. What is the formula of this alloy?

Account for the following.

Ethylamine is soluble in water whereas aniline is not.

State reasons for the following:

Aliphatic amines are stronger bases than aromatic amines.

Complete and balance the following equation:

\[\ce{C6H5NH2 + CH3COCl ->}\] ______ + ______

Complete and balance the following equation:

\[\ce{C2H5NH2 + HNO2 ->}\] ______ + ______ + ______

Draw the structure of xenon tetrafluoride molecule and state the hybridization of the central atom and the geometry of the molecule.

Calculate the emf and ΔG for the given cell at 25°C:

Cr_(s) | Cr³⁺ (0.1 M) || Fe²⁺ (0.01 M) || Fe_(s)

Given: \[\ce{E^{\circ}_{Cr^{3+}/Cr}}\] = −0.74 V, \[\ce{E^{\circ}_{Fe^{2+}/Fe}}\] = −0.44 V

(1 F = 96500 C mol⁻¹, R = 8.314 JK⁻¹ mol⁻¹)

Calculate the degree of dissociation (α) of acetic acid if its molar conductivity (Λ_m) is 39.05 S cm² mol⁻¹.

(Given \[\ce{\lambda^{\circ}_{(H^+)}}\] = 349.6 S cm² mol⁻¹ and \[\ce{\lambda^{\circ}_{(CH_3COO^-)}}\] = 40.95 S cm² mol⁻¹)

Name an important ore of silver.

How is silver extracted from its sulphide ore?

Give balanced chemical equations involved in the extraction of pure silver.

How do you convert Chlorobenzene to biphenyl?

How will you prepare 1-bromopropane from propene?

How is the following conversion carried out?

Chlorobenzene to aniline

Explain what happens when a beam of light is passed through a colloidal solution.

Explain what is observed when an electric current is passed through a colloidal sol?

Explain what is observed when an electrolyte (AlCl₃) is added to a colloidal solution of arsenious sulphide (As₂S₃).

How will you bring about the following conversion?

Benzoyl chloride to benzaldehyde.

How will you convert the following: (Give a balanced equation)

Methyl chloride to acetic acid.

How do you convert the following:

Acetic acid to Methane

A ketone A (C₄H₈O) which undergoes Iodoform reaction gives compound B on reduction. B on heating with conc.H₂SO₄ at 443 K gives a compound C which forms ozonide D. D on hydrolysis with Zn dust gives only E. Identify the compounds A to E. Write the Iodoform reaction with compound A.

A first-order reaction is 50% complete in 30 minutes at 300 K and in 10 minutes at 320 K. Calculate activation energy (E_a) for the reaction. [R = 8.314 J K⁻¹ mol⁻¹]

[Given: log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021]

Give reasons for the following statement:

Transition metals and most of their compounds show paramagnetic behaviour.

Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22, Cu = 29)

Explain the following:

K₂Cr₂O₇ acts as a powerful medium oxidising agent in acidic

The elevation in boiling point when 0.30 g of acetic acid is dissolved in 100 g of benzene is 0.0633°C. Calculate the molecular weight of acetic acid from this data. What conclusion can you draw about the molecular state of the solute in the solution?

(Given K_b for benzene = 2.53 K kg mol⁻¹, at. wt. of C = 12, H = 1, O = 16)

Determine the osmotic pressure of a solution prepared by dissolving 0.025 g of K₂SO₄ in 2 litres of water at 25°C, assuming that K₂SO₄ is completely dissociated. 

(R = 0.0821 Lit-atm K⁻¹ mol⁻¹, mol. wt. of K₂SO₄ = 174 g mol⁻¹)

An aqueous solution of a non-volatile solute freezes at 272.4 K, while pure water freezes at 273.0 K. Determine the following:

(Given K_f = 1.86 K kg mol⁻¹, K_b = 0.512 K kg mol⁻¹ and vapour pressure of water at 298 K = 23.756 mm of Hg)

1. The molality of solution
2. Boiling point of solution
3. The lowering of vapour pressure of water at 298 K.

A solution containing 1.23 g of calcium nitrate in 10 g of water, boils at 100.975°C at 760 mm of Hg. Calculate the van’t Hoff factor for the salt at this concentration.

(K_b for water = 0.52 K kg mol⁻¹, mol. wt. of calcium nitrate = 164 g mol⁻¹)

Give the IUPAC name of the following complex:

[Cu(NH₃)₄]SO₄

Give the IUPAC name of the following complex:

[Co(en)₂Cl₂]

Give the IUPAC name of the following complex:

K₃[Al(C₂O₄)₃]

With reference to the coordination complex ion [Fe(H₂O)₆]²⁺ answer the following: (at. no. of Fe = 26)

1. Give the IUPAC name of the complex ion.
2. What is the oxidation number of the central metal atom?
3. How many unpaired electrons are there in the complex ion?
4. State the type of hybridisation of the complex ion.

Write the type of isomerism exhibited by [Co(NH₃)₅(NO₂)]²⁺ and [Co(NH₃)₅ONO]²⁺ pair of complex ion.

Name the type of isomerism exhibited by the following pair of compounds:

[Cr(H₂O)₅Cl]Cl₂.H₂O and [Cr(H₂O)₄Cl₂]Cl.2H₂O

Name the type of isomerism exhibited by the following pair of compounds:

[Co(NH₃)₆][Cr(CN)₆] and [Co(CN)₆][Cr(NH₃)₆]

Using the valence bond approach, predict the shape, hybridisation and magnetic behaviour of [Ni(CO)₄]. (at. no. of Ni = 28)

What is the action of benzene diazonium chloride on phenol in alkaline medium?

Give a balanced chemical equation for the following reaction:

Diethyl ether is treated with phosphorous pentachloride.

Give a balanced chemical equation for the following reaction:

Ethyl alcohol is treated with thionyl chloride.

Give one chemical test to distinguish between the following pair of compounds:

Ethanol and dimethyl ether

Write the chemical test to distinguish between Propan-1-ol and Propan-2-ol.

Write a chemical equation to illustrate the following name reaction:

Williamson’s synthesis

Write the chemical equation for the following:

Esterification Reaction

Write the equation involved in the following reaction:

Reimer-Tiemann reaction

Identify the compounds A and B in the given reaction:

\[\ce{C2H5OH ->[Cu][\Delta] A ->[CH3COCl][anhy. AlCl3] B}\]

Identify the compounds A and B in the given reaction: