Chemistry 2012-2013 HSC Science (General) 12th Standard Board Exam Question Paper Solution

In Van Arkel method of refining metal, impure zirconium is converted to unstable volatile
compound by heating it with _______.

(A) oxygen

(B) chlorine

(C) bromine

(D) iodine

The temperature at which vapour pressure of a liquid becomes equal to the atmospheric
pressure is _______.

(A) melting point

(B) boiling point

(C) 273 K

(D) 373 K

Which of the following parameters are correct for triclinic lattice?

(A) α = β = γ = 90° and a = b = c

(B) α ≠ β ≠ γ = 90° and a ≠ b ≠ c

(C) α = γ = 90°, β ≠ 90° and a ≠ b ≠ c

(D) α ≠ β ≠ γ ≠ 90° and a ≠ b ≠ c

Which mixture is used for respiration by deep sea divers?

(A) He + O₂

(B) Ne + O₂

(C) Ar + O₂

(D) Kr + O₂

For the reaction, 2N₂O_5(g) → 4NO_2(g) + O_2(g) in liquid bromine, which of the following rate
equation is INCORRECT?

a) `-1/2 (d[N_2O_5])/dt`

b) `-1/4 (d[NO_2])/dt`

c) `(d[O_2])/dt`

d) `1/4 (d[NO_2])/dt`

For a certain reaction, ∆H = − 50 kJ and ∆S = − 80 J K^-1, at what temperature does the
reaction turn from spontaneous to non-spontaneous?

(A) 6.25 K

(B) 62.5 K

(C) 625 K

(D) 6250 K

What is the ratio of volumes of H2 and O2 liberated during electrolysis of acidified water?

(A) 1 : 2

(B) 2 : 1

(C) 1 : 8

(D) 8 : 1

Calculate ∆H° for the following reaction:

2H₃BO_3(aq) → B2O_3(s) + 3H₂O_(l)

a) H₃BO_3(aq) → HBO_2(aq) + H₂O_(l) , ∆`H_1^@` = − 0.02 kJ

b) H₂B₄O_7(s) → 2B₂O_3(s) + H₂O_(l) , ∆`H_2^@` = 17.3 kJ

c)H₂B₄O_7(s) + H₂O_(l) → 4HBO_2(aq), ∆`H_3^@` = − 11.58 kJ

Calculate molarity and molality of 6.3% solution of nitric acid having density 1.04 g cm⁻³
. (H = 1, N = 14, O = 16)

What is the action of chlorine (Cl) on the following:

Cold and dilute caustic soda

What is the action of chlorine (Cl) on the following:

Hot and concentrated caustic soda

What is the action of chlorine (Cl) on the following:

Potassium bromide solution

Calculate the number of atoms present in 2 gram of crystal which has face-centred cubic
(FCC) crystal lattice having edge length of 100 pm and density 10 gcm−3

NF₃ is possible, but NF₅ is not. Why?

State second law of electrolysis

Explain Faraday’s second law of electrolysis

Describe ‘froth floatation process’ for concentration of sulphide ore.

Distinguish between Order and Molecularity of reaction.

What are the conditions for spontaneous and non-spontaneous reactions in terms of free
energy change?

Define entropy.

Draw the structure of H₄P₂O₆ hypophosphoric acid

What is the action of heat on potassium permanganate?

State Henry’s law.

How does solubility of a gas in water varies with the temperature?

Define the following term

Schottky defect

What are Frenkel defect

Write electrode reaction and net cell reaction for fuel cell. Calculate e.m.f. of the following cell at 25 °C.

Standard reduction potential (SRP) of Zn and Cu are − 0.76 V and 0.334 V respectively

Define isotonic solutions

Derive the relation ∆H − ∆U = ∆nRT.

Define activation energy.

Calculate activation energy for a reaction of which rate constant becomes four times when temperature changes from 30 °C to 50 °C. (Given R = 8.314 JK⁻¹ mol⁻¹). 

Draw a neat, well labelled diagram of electrolytic cell for extraction of aluminium

Write electronic configuration and two uses of neon. (Z = 10)

When KOH solution is added to potassium dichromate solution the colour of solution
changes to yellow, because _______

(A) chromate ion changes to dichromate ion

(B) dichromate ion changes to chromate ion

(C) oxidation number of chromium changes from + 6 to + 4

(D) oxidation number of chromium changes from + 4 to +6

But-1-ene on reaction with HCl in the presence of sodium peroxide yields _______.

n-butyl chloride

isobutyl chloride

secondary butyl chloride

tertiary butyl chloride

3-Methylbutane-2-ol on heating with HI gives ______

2-iodo-3-methylbutane

2-iodo-2-methylbutane

1-iodo-3-methylbutane

1-iodo-2-methylbutane

IUPAC name of is C₆H₅ − CH₂ − C − CH₂ − CH₂ − CH₂ − CH₃ is _______

(A) 1-Phenylhexan-2-one

(B) 6-Phenylhexan-5-one

(C) 1-Benzylhexan-5-one

(D) Dodecan-5-one

Iodoform is used as an _______.

antiseptic

antibiotic

insecticide

anaesthetic

Stachyose is an example of _______.

(A) monosaccharides

(B) disaccharides

(C) trisaccharides

(D) tetrasaccharides

The Zieglar-Natta catalyst is used in the preparation of _______.

(A) LDPE

(B) PHBV

(C) PAN

(D) HDPE

How is phenol converted into the following?

benzene

How is phenol converted into the following?

benzoquinone

How is phenol converted into the following?

picric acid

Write mechanism of Aldol addition reaction.

Enlist the properties of glucose that can not be explained on the basis of open chain structure of it

How is nitromethane prepared from the following?

alkyl halide

How is nitromethane prepared from the following?

α-halogen carboxylic acid

How is nitromethane prepared from the following?

α-nitroalkene

How is methoxy benzene prepared from carbolic acid?

State the superiority of crystal field theory over valence bond theory.

How is Benzonitrile converted to Benzophenone?

Write a short note on Hoffmann bromamide degradation.

What are hormones?

State the function of insulin.

How are polymers classified on the basis of polymerisation process?

Explain any two chemical methods of food preservation.

Write observed electronic configuration of elements from first transition series having half
filled d-orbitals.

What is lanthanoid contraction?

Explain the cause of lanthanoid contraction?

Explain effects of lanthanoid contraction

Write the structure of melamine.

Explain the cleansing action of soaps.

Explain optical activity of lactic acid

Draw a neat, labelled energy profile diagram for SN¹ reaction mechanism.

Write applications of co-ordination compounds in medicine and electroplating.

Explain the structure of carbonyl functional group