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

In body centred cubic structure the space occupied is about

(A) 68%                                                     (B) 53%

(C) 38%                                                     (D) 32%

For a gaseous reaction the unit of rate of reaction is

(A) L atm s^-1

(B) atm mol^-1 s^-1

(C) atm s¹

(D) mol s

Which of the following compounds contain S = O as well as S = S bonds?

(A) Sulphuric acid

(B) Thiosulphuric acid

(C) Sulphurous acid

(D) Thiosulphurous acid

Which of the following solutions shows maximum depression in freezing point?

(A) 0.5 M Li₂SQ₄

(B) 1 M NaCl

(C) 0.5 M A1₂(SO₄)₃

(D) 0.5 MBaC1₂

For a chemical reaction dS=0.035 kJ/k and dH=20kJ. At what temperature does the reaction turn nonspontaneous?

5.14 K

57.14 K

571.4 K

5714.0 K

The standard e.m.f of the following cell is 0.463 V

`Cu|Cu_(1m)^(++)`

What is the standard potential of Cu electrode?

(A) 1.137 V

(B) 0.337 V

(C) 0.463 V

(D) - 0.463 V

Fe₂O₃ is reduced to spongy iron near the top of blast furance by

(A) H₂

(B) CaO

(C) SiO₂

(D) CO

Distinguish between crystalline solid and amorphous solid

State Kohlrausch Law

Write mathematical expression of molar conductivity of the given solution at infinite dilution.

Write cell reaction in lead storage battery during discharge.

Draw structure and write geometry of PCl₃ and PCl_5.

Prove that ΔH=ΔU+ΔnRT. what is the condition under which ΔU=ΔH?

Mention names and formulae of two ores of alumunium.

Derive the relationship between relative lowering of vapour pressure and molar mass of nonvolatile solute.

What is pseudo first order reaction? Give one· example of it.

Calculate the mole fraction and molality of HNO₃ in solution contaning 12.2%HNO₃ (Given atomic mases:H=1, N=13,O=16)

Consider the reaction

`3I_((aq))^-) +S_2O_8^(2-)->I_(3(aq))^-) + 2S_2O_4^(2-)`

At particular time t, `(d[SO_4^(2-)])/dt=2.2xx10^(-2)"M/s"`

What are the values of the following at the same time?

a. `-(d[I^-])/dt`

b. `-(d[S_2O_8^(2-)])/dt`

c. `-(d[I_3^-])/dt`

300 M mol of perfect gas occupies 13 L at 320 K. Calculate the work done in joules when the gas expands-

(a) isothermally against a Constant external pressure of 0.20atm.

(b) isothermal and reversible process.

(c) into vaccum until the volume of gas is increased by 3L (R=8.314J mol^-1 K^-1)

What is the action of Excess of air on ammonia ?

What is the action of Excess of chlorine on ammonia?

What is the action of Na Metal on ammonia? 

Explain with reason sign conventions of ΔS in the following reaction

N_2(g) + 3H_2(g) → 2NH_3(g)

Explain with reason sign conventions of ΔS in the following reaction

CO_2(g) → CO_2(g)

Explain the following term

Smelting

Explain the following term

Flux

Gold occurs as face centred cube and has a density of 19.30 kg dm^-3. Calculate atomic radius of gold (Molar mass of Au = 197)

a. Explain the trends in the following properties with reference to group 16:

1 Atomic radii and ionic radii

2 Density

3 ionisation enthalpy

4 Electronegativity

b. In the electolysis of AgNO₃ solution 0.7g of Ag is deposited after a certain period of time. Calulate the quantity of electricity required in coulomb. (Molar mass of Ag is 107.9g mol^-1)

Explain the term osmosis.

ln which pair highest oxidation states of transition metals are found:

nitriles and chlorides

fluorides and chlorides

fluorides and oxides

nitriles and oxides

which of the following carbocations is least stable?

(A) 

(B)

(C)

(D)

Compound having general formula is called

(A) diester

(B) acid anhydride

(C) hemiacetal

(D) acetal

The complex ion `[Co(H_2O)_5 (ONO)]^(2+) `

(A) linkage isomer

(B) ionisation isomer

(C) co-ordination isomer

(D) geometrical isomer

Inflammation of the tongue is due to the deficiency of:

Vitamin B₁

Vitamin B₂

Vitamin B₅

Vitamin B₆

Identify the compound 'B' in the following series of reaction:

(A) n-propyl chloride

(B) Propanamine

(C) n-propyl alcohol

(D) Isoproply alcohol

Which of the following reagents is best for the following conversion?

(A) LiAlH₄

(B) 

(C) H₂/Ni, 453 K

(D) Zn-Hg+HCl_(con)

Calculate magnetic moment of  `Fe_((aq))^(2+) ion (Z=26).`

How is ethanol prepared from methanal by using Grignard reagent?

Write the chemical reaction to prepare novolac polymer.

Why does p-nitrochlorobenzene undergo displacement reactions readily with attack of nucleophilic HO^{Θ ion}?

What is the action of bromine in alkaline medium on

i. CH₃CH₂NO₂

ii. 

Define antioxidants?

How is 4-methylpent-3-en-2-one obtained from propan-2-one?

What are hormones?

Write the structure of simple triglycerides.

Write the different oxidation states of manganese.

Why +2 oxidation state of manganese is more stable?

How are the following compounds prepared?

benzaldehyde from benzene

How are the following compounds prepared?

acetophenone from benzene

How are the following compounds prepared?

benzaldehyde from benzoyl chloride

Write the structure of a nucleotide

Write the structure of a nucleoside

Define complex lipids

Write the fomulae of the following compounds

Sodium hexanitrito- N - cobaltate (III)

Write the fomulae of the following compounds :

Tetraaquodichlorochromium (III) chloride

Write the fomulae of the following compounds

Potassium tetracyanoaurate (III) ion

Explain the following term: Homopolymers

Explain the following term: Elastomers

Explain the mechanism of cleansing action of soaps.

Write balanced chemical equations for the action of phosphorous trichloride on propan-2-ol

Write balanced chemical equations for the action of hydrogen bromide on styrene in the presence of a peroxide

Write balanced chemical equations for the action of methyl bromide on silver propanoate

Write a short note on Hoffmann bromamide degradation.

Explain the mechanism of action of hydroiodic acid on 3-methylbutan-2-ol.

Mention 'two' uses of propan-2-one.