Question # 1

Recrystallization is the most common technique of purification of solid organic substances Which of the following statements is not related with characteristics of a suitable solvent.

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It dissolves the substance on heating

It readily allows it to separate out in the form of crystal on cooling

It does not react chemically with substance

It does dissolve the impurities.

Which of the following reacts with excess oxygen to form a normal oxide.

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Li

Na

K

Rb

The hydrogen bond is strongest in.

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O - H .............S

S - H.............O

F- H....................F

F - H...............O

Hydrogen at the moment of its generation is generally called.

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Protium

Nascent hydrogen

Atomic hydorgen

Heavy hydrogen

The pKa of an acid having ionization constant 1 x 10^-5 is

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-5

5

9

-9

Which of the following species has highest bond energy.

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H2

T2

D

Cl

The electron gain enthalpy of chlorine is -349 Kj mol-1 ionization energy of Cl would be.

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-349 kJ mol -1

349 kJ mol-1

-698 kJ mol-1

698 kJ mol-1

Which of the following pollutant result from combustion of fossil fuels.

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SO2

NOx

CO

All above

When a strong beam of light is passed through a colloidal solution, the light will

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Be reflected

Be scattered

Pass unchanged

Be dispersed

Which element amongst the following has the highest boiling point.

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Na

Mg

Ca

K

Metals are

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Transparent

Tranalucant

Opaque

None of above

White Phosphorus is kept under

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Cold water

Ammonia liquor

Ethanol

Kerosene

A molecule MX4 has a square planar shape, The number of non bonding pairs of electrons around M is .

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2

1

0

3

The reagent which can be used to distinguish acetophenone from benzophenone is.

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2,4 -dinito phenyl hydrazine

Li AIH4

Benedict reagetn

I2 and Na2CO3

Which of the following substance is released into environment in the nuclear power plants.

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Iodine -131

Argon - 41

Sr-90

Cs- 137

All above

If for a solution of an electrolyte. It is the transport number of the cation, then the transport number of the anion I, is equal to

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t/2

1 - t+

1 + t+

(i -t) /2

Which of the following reaction cannot be used for the synthesis of a amino acids.

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Gabriel phthalimide

Streckers synthesis

Sorensen synthesis

Schmidt synthesis

Xe reacts directly with

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O2

Cl2

F2

Br2

Which of the following technique is used to separate substance based on their charge to mass ratio.

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HPLC

HPTLC

GC

Electrophoresis

Which of the following statement is not related with high quantum yield reasons.

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Formation of reactive intermediates which may act as catalyst

The active molecules may collide with other molecules and activates these molecules.

The reaction may be exothermic and heat evolve may activate other molecule

The primary photo chemical process may be reversed

Which of the following devoice is used to measure potential difference between celctrodes.

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Polarimetre

Conductometer

Voltmeter

Photometer

Which of the following statement is not correct with respect to electrometric effect.

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It is permanent effect

It is brought into play instantaneously at the demand of attacking reagent

It proceeds a polar addition reaction

The original electronic condition is restored after the removal of tacking regent.

Halogens are coloured because.

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They are strong oxidant

Their molecules are held together by weak van der Waals forces

Their atoms absorb radiations form visible range causing the excitation of valence electrons to higher energy of levels

Their molecules absorb light radiation forming the oxcited state.

What ASTM test for compression is designated for plastics.

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D 638

D 695

D 790

D 732

Which of the following statement is not relevant with nitrous oxide.

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It is a colorless and odourless gas

It is non toxic gas

It is present in the atmosphere in higher concentration

It has high reactivity in the lower atmosphere

A man has to think of alternate sources of energy due to

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Shortage of vehicles

Shortage of fossil fuels

Construction of house

Running of power plant

What of the following is not a Lewis base.

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CN-

AlCl3

NH3

ROH

Pick out incorrect statemtn about K2r2O7

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It oxidizes acidified solution of H2S to S

It oxidizes Ki TO i2

It oxidizes HCl to Cl2

It gives oxygen, when treated with cold conc. H2SO4

The role of the mineral cryolite Na2AlF6 in the Hall process for aluminum production is.

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It is the source of aluminum

it is a chemical reducing agent

It forms a slag to remove impuriteis

In the molten state, it is a solvent for alumina Al2O3

Which of the following statements is not correct. with respect to resonance.

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The position of atomic nuclei mus be same

The limiting structures must have same number of paired and unpaired electrons.

The energy of the various limiting structures must contribute equally

All above

The correct order of ionization energies of alkali metals is.

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Li > Na > K > Rb

Na > K > Rb > Li

Rb > K > Na > Li

Rb > K > Li > Na

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