Chemistry 2014-2015 HSC Science (Electronics) 12th Standard Board Exam Question Paper Solution

p - type semi-conductors are made by mixing silicon with impurities of-

1. germanium
2. boron
3. arsenic  
4. antimony

Amongst the following identify the criterion for a process to be at equilibrium -

1. ΔG < 0
2. ΔG > 0
3. ΔS_total=0
4. ΔS < 0

Colligative property depends only on ........................ in a solution.

Number of solute particles.

Number of solvent particles.

Nature of solute particles

Nature of solvent particles

The charge of how many coulomb is required to deposit 1.0 g of sodium metal (molar mass 23.0 g mol^-1) from sodium ions is -

1. 2098
2. 96500
3. 193000
4. 4196

What is the chemical composition of malachite?

1. CuO . CuC0₃
2. Cu(OH)₂ CuC0₃
3. CuO.Cu(OH)₂         
4. Cu₂O . Cu(OH)₂

The element that does NOT exhibit allotropy is

1. As
2. Sb
3. Bi
4. N

The integrated rate equation for first order reaction is A → products

`k=2.303t log_10  [A]_@/[A]_t `

`k=-1/tl_n[A]_t/[A]_0`

v`k=2.303/t log_10  [A]_t/[A]_0`

 `k=1/tl_n[A]_t/[A]_0`

Define the Enthalpy of fusion

Define the Enthalpy of atomization

Derive van’t Hoff general solution equation 

Explain impurity defect in stainless steel with diagram

Derive the relation between half life and rate constant for a first order reaction

Draw neat and labelled diagram of dry cell.

Explain the structure of sulphur dioxide.

What is calcination?

Explain calcination with reactions.

Arrange the following reducing agents in the order of increasing strength under standard state conditions. Justify the answer 

Determine whether the reactions with the following ΔH and ΔS values are spontaneous or non-spontaneous. State whether the reactions are exothermic or endothermic.

(a) ΔH = -110kJ, ΔS = + 40JK^-1 at 400 K

(b) ΔH = + 40kJ, ΔS = -120JK^-1 at 250K

1.0 x10^-3Kg of urea when dissolved in 0.0985 Kg of a solvent, decreases freezing point of the solvent by 0.211 k. 1.6x10 Kg of another non-electrolyte solute when dissolved in 0.086 Kg of the same solvent depresses the freezing point by 0.34 K. Calculate the molar mass of the another solute. (Given molar mass of urea = 60)

Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law with t_1/2= 3 hours. What fraction of the sample of sucrose remains after 8 hours?

Explain how does nitrogen exhibit anomalous behaviour amongst group 15 elements.

Niobium crystallises as body centred cube (BCC) and has density of 8.55 Kg / dm^-3 . Calculate the attomic radius of niobium.

(Given : Atomic mass of niobium = 93).

Write one statement of first law of thermodyamics and its mathematical expression.

Write the reactions involved in the zone of reduction in blast furnace during extraction of iron.

Write molecular formulae and structures of Dithionic acid

Write molecular formulae and structures of the Peroxy monosulphuric acid

Write molecular formula and structure of Pyrosulphuric acid 

Write molecular formulae and structures of the Dithionous acid

Calculate E_cell and ΔG for the following at 28°C :

Mg_(s) + Sn²⁺( 0.04M ) → Mg²⁺( 0.06M ) + Sn_(s)

E°_cell = 2.23V. Is the reaction spontaneous ?

Identify the product ‘D’ in the following sequence of reactions:

`H3C-CH2-CH2-Cl (Alc)/(KOH)'B'(HBr)/()'C'(Na)/(Ether)’D'`

1. 2,2 - dimethyl butane  
2. 2,3- dimethylbutane
3. hexane                           
4. 2,4 - dimethylpentane

Which of the following complexes will give a white precipitate on treatment with a solution of barium nitrate?

1. [Cr(NH₃)₄SO₄] Cl
2. [Co(NH₃)₄Cl₂] NO₂
3. [Cr(NH₃)₄Cl₂]SO₄
4. [CrCl₂(H₂O)₄]Cl

What is the geometry of chromate ion?

1. Tetrahedral                    
2. Octahedral
3. Trigonal planer              
4. Linear

Primary and secondary nitroalcanes containing α - H atom show property of -

1. chain isomerism
2. tautomerism
3. optical isomerism
4. geometrical isomerism

In phenol carbon atom attached to -OH group undergoes -

1. SP³ hybridisation          
2. SP hybridisation
3. SP² hybridisation
4. No hybridisation

Identify the strongest acid amongst the followings:

1. Chloroacetic acid          
2. Acetic acid
3. Trichloroacetic acid
4. Dichloroaceticacid

Which of the following vitamins is water soluble?

1. A
2. D
3. E
4. B

Write a note on Friedel Craft’s acylation.

How is ethyl amine prepared from methyl iodide?

What are antibiotics? Give ‘two’ examples

Explain, why are boiling points of carboxylic acids higher than corresponding alcohols

How are proteins classified on the basis of molecular shapes?

What are interstitial compounds ?

Why do interstitial compounds have higher melting points than corresponding pure metals?

Write the structures and IUPAC names of the :Adipic acid compound

Write the structures and IUPAC names of the α - methyl butyraldehyde.

Explain with examples, branched and linear polymers.

On the basis of valence bond theory explain the nature of bonding in [CoF₆]³ ion.

Write the IUPAC name of [ Co(NO₂)₃(NH₃)₃ ].

Define lanthanoid contraction.

Explain effects of lanthanoid contraction

What are the consequences of lanthanoid contraction?

Write mechanism of Aldol addition reaction.

Define carbohydrates.

What are reducing and non-reducing sugars?

What are biodegradable polymers and non-biodegradable polymers? Write ‘one example’ of each.

Explain cationic detergents.

How is carbolic acid prepared from the given compounds :

Aniline

How is carbolic acid prepared from the given compounds :

Chlorobenzene and steam at 698K?

Draw structure of DDT.

Write the environmental effects of DDT.

Mention ‘two’ physical properties of carbolic acid.