Chemistry (Theory) 2014-2015 ISC (Commerce) Class 12 Question Paper Solution

The more _____ the standard reduction potential of a metal, the ____ is its ability to displace hydrogen from acids.

Both ccp and hcp are ______ packings and occupy about ______% of the available space.

The solubility of silver chloride _______ in the presence of sodium: chloride because of ___________

Benzaldehyde undergoes ________ reaction on treatment with concentrated sodium hydroxide because it has _______ atom

The transition metals show _________ character because of the presence of unpaired· electrons and Cu⁺ is ____________ because of its electronic configuration is [Ar]3d¹⁰

The molal freezing point constant of water is 1·86 K kg mol^-1. Therefore, the freezing point of 0·1 M NaCl solution in water is expected to be:

1) -1.86°C

2) -0.372 °C

3) -0.186 °C

4) +0.372 °C

For a first-order reaction, the rate constant for decomposition of `N_2O_5` is `6 xx 10^(-4) sec^(-1)`.The half-life period for the decomposition in seconds is:

1) 11·55

2) 115·5

3) 1155

4) 1·155

When acetaldehyde is treated With Grignard reagent, followed by hydrolysiS-the product formed is:

1) Primary alcohol

2) Secondary alcohol

3) Carboxylic acid

4) Tertiary alcohol

The geometry of XeF₆ molecule and_ the hybridization of Xe atom in the molecule.is:

1) Distorted octahedral and `sp^3d^3`

2) Square planar and `sp^3d^2`

3) Pyramidal and `sp^3`

4)Octahedral and `sp^3d^3`

In the complexes `[Fe(CN)_6]^(3-)` and `[pt(en) (H_2O)_2(NO_2 (Cl)^(2+)]``the respective oxidation numbers of central metal atoms are

1) +3 and +4

2) +6 and + 4

3) +6 and +3

4) +3 and + 3

What is the effect of temperature on the ionic, product of water? How will it change the pH value of a neutral solution?

How many hours does it take to reduce 3 moles of Fe³⁺ to Fe²⁺ with 2.0 A current intensity?

How is urea prepared by Wohler synthesis?

Two liquids A and B form type II non-ideal solution which shows a minimum in its temperature-mole fraction plot (T-χ diagram). Can the two liquids be completely separated by fractional distillation?

The aqueous solution of sodium acetate is basic. Explain.

Match the following:

A solution containing 0.5 g of KCl dissolves in 100 g of water and freezes at −0·24°C. Calculate the degree of dissociation of the salt. (K_f for water = 1.86°C) Atomic weights, K = 39, Cl = 35.5.

If 1.71 g of sugar (molar mass = 342) are dissolved in 500 ml of an aqueous solution at 300 K, what will be its osmotic pressure?

0.70 g of an organic compound, when dissolved in 32 g of acetone, produces an elevation of 0.25°C in the boiling point. Calculate the molecular mass of the organic compound (K_b for acetone = 1.72 K kg mol⁻¹).

What is the difference between the order of a reaction and the molecularity of a reaction?

A substance decomposes by following first order kinetics. If 50% of the compound is decomposed in 120 minutes, how long will it take for 90% of the compound to decompose?

Name the crystal structure of the copper metal.

Chromium metal crystallises with a body centred cubic lattice. The edge length of the unit cell is found to be 287 pm. Calculate the atomic radius. What would be the density of chromium in g/cm³? (atomic mass of Cr = 52.99)

Why does sodium chloride on heating with sodium vapours acquire yellow colour?

The equilibrium constant for the reaction: 

`N_(2(g)) + 3H_(2(g)) ⇌ 2NH_(3(g)) at 715 K, is 6.0 xx 10^(-2)`

If, in a particular reaction, there ate 0·25 mol L^-1 of H₂. and 0·06 mol L^-1 of NH₃ present, calculate the concentration of N₂ at equilibrium

Calculate the concentration of OH^- ions in solution when [H⁺] = 6.2 x 10^-2L mol L^-1.

State the Le Chatelier's principle.

For a crystal of sodium chloride, state the type of lattice in which it crystallises.

What is the coordination number of sodium and chloride ions in sodium chloride crystals?

How many sodium ions and chloride ions are present in a unit cell of sodium chloride crystal?

For a crystal of sodium chloride, state the structural arrangement of the sodium chloride crystal.

Consider the following reaction:

`N_2O_(4(g)) + Heat ⇌ 2NO_(2(g))`

How is the Composition of equilibrium mixture affected by:

1) a change in temperature

2) a change in pressure

3) change in concentration of N₂O₄

The specific conductance of a 0.01 M solution of acetic acid at 298 K is 1.65 × 10⁻⁴ ohm⁻¹ cm⁻¹. The molar conductance at infinite dilution for H⁺ ion and CH₃COO⁻ ion is 349.1 ohm⁻¹ cm² mol⁻¹ and 40.9 ohm⁻¹ cm² mol⁻¹ respectively.

Calculate:

1. Molar conductance of the solution.
2. The degree of dissociation of CH₃COOH.
3. A dissociation constant for acetic acid.

Calculate the e.m.f. of the following cell reaction at 298 K:

\[\ce{Mg_{(s)} + Cu{^{2+}} (0.0001 M) -> Mg{^{2+}} (0.001M) + Cu_{(s)}}\]

The standard potential (E°) of the cell is 2.71 V.

The solubility product (K_sp) of BaSO₄ is 1.5 X 10^-9.Calculate the solubility of barium sulphate in pure water and in 0.1 M BaCl₂.

When NH₄ Cl and NH₄OH are added to a solution containing both, Fe³⁺ and Ca²⁺ ions, which ion is precipitated first and why?

Dissociation of H₂S is suppressed in acidic medium.

Write the IUPAC name of the following coordination compound:

[Cr(NH₃)₄(H₂O)₂]Cl₃

Write the IUPAC name of the following coordination compound:

[PtCl₂(NH₃)₄][PtCl₄]

State the hybridization and magnetic property of [Fe(CN)₆]³⁻ ion according to the valence bond theory.

What type of isomers are `[Co(NH_3)_5Br]SO_4`and `[Co(NH_3)_5SO_4]Br`?. Give a  chemical test to distinguish between them.

Write the structures of optical isomers of the complex ion [Co(en)₂Cl₂]⁺.

Give balanced chemical equations for Fluorine is passed through cold, dilute NaOH solution

Give balanced chemical equations for  Hydrogen peroxide is treated with an acidified KMnO₄ solution.

Give balanced chemical equations for Sulphuric acid is treated with hydrogen sulphide

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

Name the important ore of silver. Write all the steps and reactions involved in the Cyanide process for the extraction of silver from its ore.

Why do transition metal ions possess a great tendency to form complexes?

The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.

How can the following conversions be brought about

Glycerol to formic acid

How can the following conversion be brought about?

Chlorobenzene to phenol

How can the following conversions be brought about:

Diethyl ether to ethanol

How can the following conversions be brought about:

Phenol to aniline.

How is iodoform prepared from ethanol? Give balanced equation.

What.will be the product fonned when chlorobenzene is heated with sodium metal in the presence of dry ether?

Identify the compounds A, B, C, D, E, and F:

\[\ce{CH3COCH3->[Conc.HNO3][(O)]A}\]

\[\ce{->[SOCl2]B}\]

\[\ce{->[NH3]C}\]

\[\ce{->[LiAlH4]D}\]

\[\ce{->[HNO2]E}\]

\[\ce{->[CH3COCl]F}\]

Write the equation involved in the following reaction:

Reimer-Tiemann reaction

Write the chemical equations to illustrate the following name reactions : Rosenmund reduction

Give ba1anced equations for the following name reactions:

Hoffmann’s degradation reaction

Give of chemical test to distinguish between the following pairs of compounds:

Ethylamine and diethylamine

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

Acetaldehyde and benzaldehyde

Arrange the following compounds in the ascending order of their basic strength and give reasons for your answer:

Methylamine, Aniline, Ethylamine, Diethyl ether

Name the monomers and the type of polymerization in each of the following polymers:

Polyester

Name the monomers and the type of polymerization in each of the following polymers:

Bakelite

An organic compound A with molecular formula C₂H₇N on reaction with nitrous acid gives a compound B. Bon controlled oxidation gives compound C. C reduces Tollen's -reagent to give silver mirror and D. B reacts with D in the presence of concentrated sulphuric acid to give sweet smelling compound E. Identify A, B, C, D. and E. Give the reaction of C with ammonia

Give balanced equations for the following reactions:

How.will you Convert ethylamine to methylamine?

Give balanced equations for the following reaction:

What is the effect of denaturation on the structure of proteins?·

Give balanced equations for the following reactions:

Name the nitrogen base residues present in DNA

Give balanced equations for the following reactions:

Aniline is treated with nitrous acid and HCl at the low temperature

Give balanced equations for the following reactions:

Acetyl chloride is treated with ethyl alcohol.

Give balanced equations for the following reactions:

Formaldehyde is treated with ammonia.