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18901.

The sublimation energy of l_(2)(s) is 57.3 kJ/mol and the enthalpy of fusion is 15.5 kJ/mol. The enthalpy of vaporisation of l_(2) is

Answer»

41.8 kJ/mol
`-41.8` kJ/mol
72.8 kJ/mol
`-72.8` kJ/mol

Solution :According to Hess's law, total HEAT changes during a chemical reaction are independent of path of reaction.
Given, `I_(2)(s) to I_(2)(g),DeltaH_(1)=57.3kJ//mol`. ..(i)
`I_(2)(s)toI_(2)(L),DeltaH_(2)=+15.5kJ//mol`. . . (ii)
REQUIRED EQUATION `I_(2)(l)toI_(2)(g)`,
Substract Eq. (ii) from eq. (i)
`therefore I_(2)(l) to I_(2)(g),Deltah=57.3+(-15.5)=+41.8kJ//mol`
Discussion
18902.

Yellow phsophorus reats alkali on boiling in an inert atmosphereliberates ………………… .

Answer»

PHOSPHOROUS acid
Phosphoric acid
PHOSPHINE
Pyrophosphoric acid

Solution :Phosphine
Discussion
18903.

Which of the following reaction equilibrium is favoured in forward direction?

Answer»




`EtOH+NaOHhArrEtoverset(ɵ)(O)Noverset(o+)(a)+H_(2)O`

SOLUTION :Acid-base REACTION TAKES place from the siode of strong acid-strong base to weak acid-weak base.
Discussion
18904.

Why are Cd^(2+) salts white ?

Answer»

Solution :`Cd^(2+)`SALTS are white because it has COMPLETELY filled d ORBITALS `(d^(10))`.
Discussion
18905.

Whichcompound gives most unstable enol-

Answer»




ANSWER :A
Discussion
18906.

Which of the following is not a target molecule for drug function in body ?

Answer»

Carbohydrates
Lipids
Vitamins
Proteins

Solution :DRUGS USUALLY interact with BIOMOLECULES such as carbohydrates, lipids, proteins and nucleic acids. These are called target molecules or DRUG targets .
Discussion
18907.

Which type of isomerism is shown by 2,3-dichlorobutane?

Answer»

Diastero
Geometrical
OPTICAL
Strucutral

ANSWER :C
Discussion
18908.

Which solution has higher concentration, 1molar or 1 molal solution of the same solute? Give reason?

Answer»

Solution :In aqueous solution, 1M solution means 1 mole of the solute in 1000 cc of the solution whereas 1 m solution means 1 mle of the solute in 1000 g of water ( = 1000 cc of water). TOTAL volume of 1 m solution GT 1000 cc due to presence of extra 1 mole of the solute. Hence, numer of moles/cc in 1 m solution will be less than that in 1 M solution. In other words, 1 M is more concentrated than 1 m.
In non-aqueous solution, 1 M can be GREATER than, less than or equal to 1 m, depending UPON the DENSITY of the solution.
Discussion
18909.

Two mole of an ideal gas originally at a volume of 8 L at 1000 K , is allowed to expand adiabatically until final volume is 24 L . For the gas C_(v) = 1.5R . Calculate values of DeltaS for the process when: (i) The expansion takes place reversibly. (ii) The change in volume involves a free expansion. Sum of DeltaS of these two case is _________. (Used :e^(1.09) = 3and 1.09 xx 8.314=9)

Answer»


SOLUTION :N//A
Discussion
18910.

The value of van der Waals' constant 'a' for gases O_2, N_2 , NH_3 and CH_4 re 1.360,1.390,4.170 and 2.253 litre^2 atm mol^(-2) respectively. The gas which can most easily be liquefied is :

Answer»

`O_2`
`N_2`
`NH_3`
`CH_4`

ANSWER :C
Discussion
18911.

Which of the following is formed by the action of water on Na_(2)O_(2)?

Answer»

`H_(2)`
`O_(2)`
`N_(2)`
`CO_(2)`

ANSWER :B
Discussion
18912.

The specific conductance of a 0.20 M KCl solution at 298 K is 0.0248 S cm^(-1) . What will be its molar conductance?

Answer»

`1240 S cm^(2 ) mol^(-1)`
`1.24 S cm^(2 ) mol^(-1)`
`124 S cm^(2) mol^(-1)`
`12400 S cm^(2) mol^(-1)`

Answer :C
Discussion
18913.

Using the unit conversion factors, express (i) 1.54 mm s^(-1) in pm mus^(-1) (ii) 2.66 g cm^(-3) in mum^(-3)

Answer»


Solution :(i) `(1.54mm)/(1s)xx(1cm)/(10MM)xx(1m)/(100CM)xx("1 pm")/(10^(-12)m)xx(10^(-6)s)/(1mus)=1.54xx10^(3)" pm"mus^(-1)`
(ii) `(2.66g)/(1cm^(3))xx(1mug)/(10^(-6)g)xx(100cm)/(1m)xx(100cm)/(1m)xx(100cm)/(1m)xx(10^(-6)m)/(1mum)xx(10^(-6)m)/(1mum)xx(10^(-6)m)/(1mum)=2.66xx10^(-6)MUG mum^(-3).`
Discussion
18914.

Which of the following are the best methods for the preparation of cument (A) ?

Answer»




SOLUTION :a. Pdoducts would be a mixture of `(I)` and `(II)` (as in Q. No. 2) `(B), (c), (d)` would PRODUCE STABLE
Discussion
18915.

Which product of the following reaction is used to treat acid indigestion ?

Answer»

`Al_(4)C_(3) + H_(2)O rarr CH -= CH + Al(OH)_(3)`
`CaC_(2) + H_(2)O rarr CH -= CH + CA(OH)_(2)`
`Mg_(4)C_(3) + H_(2)O rarr CH_(3)C -= CH + Mg(OH)_(2)`
All true

Answer :C
Discussion
18916.

The titration of oxalic acid in solution is possibile with KMnO_4 in presence of H_2SO_4 but the titration in presence of HCl does not give satisfactory result because.

Answer»

Chlorine of HCl is oxidised by oxalic ACID.
` H^`+ of HCl is reduced to `H^2` by `MnO_4`.
`MnO_4` is reduced to `MN^(2+)`by HCl.
Oxalic acid is oxidised to `CO_2` and `H_2O` by HCl.

Answer :C
Discussion
18917.

What happen when alcoholic KCN reacts with Benzaldehyde? (or) explain Benzoin condensation.

Answer»

Solution : BENZALDEHYDE reacts with alcoholic KCN to FORM BENZOIN.
Discussion
18918.

Which equation represents an example of Friedel - Crafts reaction?

Answer»

`C_6H_6+C_2H_5Cl OVERSET(AlCl_3)rarrC_6H_5C_2H_5+HCl`
`C_2H_5OH+HCloverset(ZnCl_2)rarrC_2H_5Cl+H_2O`
`C_2H_5Cl+CH_3COCloverset(AlCl_3)rarrC_6H_5COCH_3+Cl_2`
`C_2H__5Br+Mgoverset("ETHER")rarrC_2H_5MgBr`

ANSWER :A
Discussion
18919.

What amount of substance containing 60% NaCl, 37% KCl should be weighed out for analysis so that after the action of 25 ml of 0.1N AgNO_(3) solution, excess of Ag^(+)is back titrated with 5 ml of NH_(3)SCN solution? Given that 1 ml of NH_(4)SCN = 1.1 ml of AgNO_(3). [AgNO_(3)+NaSCN rarr AgSCN + NaNO_(3) ]

Answer»


ANSWER :0.1281g
Discussion
18920.

When pinacol is treated with dilute H_(2)SO_(4), a re-arangement reaction takes place which leads to the formation of a ketone. CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)C-CH_(3)overset(H_(2)SO_(4))rarrCH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)C-overset(CH_(3))overset(|)C-CH_(5) This reaction involves re-arrangement of carbocation Step 1: CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))overset(+)overset(OH_(2))overset(|)C-CH_(2)rarrCH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(+)C-CH_(3) Step 2: Carbocation rearrange by hydride, alkyl shift to get as stable as they can. Stability is the driving force for re-arrangement migration of bond may also oC Cur. Where by ring expansion and ring contraction takes place. The relief of strain can provide a powerful driving force for re-arrangement. What will be the product of following reaction

Answer»



both
None

Solution :N//A
Discussion
18921.

When pinacol is treated with dilute H_(2)SO_(4), a re-arangement reaction takes place which leads to the formation of a ketone. CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)C-CH_(3)overset(H_(2)SO_(4))rarrCH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)C-overset(CH_(3))overset(|)C-CH_(5) This reaction involves re-arrangement of carbocation Step 1: CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))overset(+)overset(OH_(2))overset(|)C-CH_(2)rarrCH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(+)C-CH_(3) Step 2: Carbocation rearrange by hydride, alkyl shift to get as stable as they can. Stability is the driving force for re-arrangement migration of bond may also oC Cur. Where by ring expansion and ring contraction takes place. The relief of strain can provide a powerful driving force for re-arrangement. What will be the product of following reaction R is:

Answer»



Both
None

Solution :N//A
Discussion
18922.

When pinacol is treated with dilute H_(2)SO_(4), a re-arangement reaction takes place which leads to the formation of a ketone. CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)C-CH_(3)overset(H_(2)SO_(4))rarrCH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)C-overset(CH_(3))overset(|)C-CH_(5) This reaction involves re-arrangement of carbocation Step 1: CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))overset(+)overset(OH_(2))overset(|)C-CH_(2)rarrCH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(+)C-CH_(3) Step 2: Carbocation rearrange by hydride, alkyl shift to get as stable as they can. Stability is the driving force for re-arrangement migration of bond may also oC Cur. Where by ring expansion and ring contraction takes place. The relief of strain can provide a powerful driving force for re-arrangement. What will be the product of following reaction S is:

Answer»



Both
None

Solution :N//A
Discussion
18923.

When pinacol is treated with dilute H_(2)SO_(4), a re-arangement reaction takes place which leads to the formation of a ketone. CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)C-CH_(3)overset(H_(2)SO_(4))rarrCH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)C-overset(CH_(3))overset(|)C-CH_(5) This reaction involves re-arrangement of carbocation Step 1: CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))overset(+)overset(OH_(2))overset(|)C-CH_(2)rarrCH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(+)C-CH_(3) Step 2: Carbocation rearrange by hydride, alkyl shift to get as stable as they can. Stability is the driving force for re-arrangement migration of bond may also oC Cur. Where by ring expansion and ring contraction takes place. The relief of strain can provide a powerful driving force for re-arrangement. What will be the product of folowing reaction CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-CH_(2)-Broverset(NaOH)rarrP,P is:

Answer»

`CH_(3)-UNDERSET(CH_(3))underset(|)C=CH-CH_(3)`
`CH_(3)-underset(CH_(3))underset(|)CH-CH=CH_(2)`
Both of these
None of these

Solution :N//A
Discussion
18924.

When pinacol is treated with dilute H_(2)SO_(4), a re-arangement reaction takes place which leads to the formation of a ketone. CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)C-CH_(3)overset(H_(2)SO_(4))rarrCH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)C-overset(CH_(3))overset(|)C-CH_(5) This reaction involves re-arrangement of carbocation Step 1: CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))overset(+)overset(OH_(2))overset(|)C-CH_(2)rarrCH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(OH)overset(|)C-underset(CH_(3))underset(|)overset(+)C-CH_(3) Step 2: Carbocation rearrange by hydride, alkyl shift to get as stable as they can. Stability is the driving force for re-arrangement migration of bond may also oC Cur. Where by ring expansion and ring contraction takes place. The relief of strain can provide a powerful driving force for re-arrangement. What will be the product of following reaction CH_(3)-underset(H)underset(|)overset(OH)overset(|)C-underset(H)underset(|)overset(OH)overset(|)CH_(3)overset(H_(2)SO_(4))rarrQ Q is:

Answer»

`CH_(3)-UNDERSET(O)underset(||)C-CH_(2)-CH_(3)`
`CH_(3)-underset(OH)underset(|)C=CH-CH_(3)`
Both
None

SOLUTION :N//A
Discussion
18925.

Whichof thefollowingis thecorrectsequenceof stepinthehalogationofan alkane ?

Answer»

PROPAGATION , intiation , termination
intitation , temination, propagation
INITATION ,propagation, temination
propagation , temnation , INITIATION

ANSWER :C
Discussion
18926.

Which of the following is not present in mineral

Answer»

`KNO_(3)`
`CaCO_(3)`
NaCl
CaO

Answer :A
Discussion
18927.

what will be the change of entropy Delta_(r)S^(@)at 298 K for the reaction in which urea is formed from NH_(3) and CO_(2) ? 2NH_(3)(g)+ CO_(2)(g) to NH_(2)CONH_(2)(aq)+H_(2)O(l)[given ,the standard entropy ofNH_(2)CONH_(2)(aq) , CO_(2)(g), NH_(3)(g)and H_(2)O(l)are 174.0 , 213. 7, 192.3 and 69.9 JK^(-1)mol^(-1) respectively]

Answer»

` 200 JK^(-1) mol ^(-1)`
`-35.44JK^(-1) mol^(-1)`
`-354.4 JK^(-1) mol ^(-1)`
`425.2 JK^(-1) mol^(-1)`

Solution :for the given change ` Delta_(r)S^(@)= sumn_(p)S_(p)^(@)- sumn_(R)S_(R)^(@)`
`S_(NH_(2)CONH_(2))^(@)+ S_(H_(2)O)^(@)-[2xxS_(NH_(3))^(@)+ S_(CO_(2))^(@)]`
` 174.0 + 69.9 -[2xx192.3+213.7]`
`354.4 JK^(-1)mol^(-1)`
Discussion
18928.

The volume strength of 1.5 " N " H_(2)O_(2) solution is

Answer»

`4.8`
`8.4`
`3.0`
`8.0`

ANSWER :B
Discussion
18929.

When the following aldohexose exists in its D-configuration, the total number of stereoisomers in its pyranose form is : CHO - CH_(2) - CHOH - CHOH- CH_(2)OH

Answer»


SOLUTION :
Thus, TOTAL number of STEREOISOMERS in pyranose FORM of D-configuration `=2^(3)=8`
Discussion
18930.

Which of the following plots represents an ideal binary mixture?

Answer»

Plot of `"P"_("TOTAL")V//s" " 1//"X"_("B")` is linear (`"X"_("B")`= mole fraction of 'B' in liquid phase).
Plot of `"P"_("total")v//s" " 1//"X"_("B")` is linear (`"Y"_("B")`= mole fraction of 'A' in vapour phase)
Plot of `1/("P"_("total"))v//s" Y"_("A")` is linear
Plot of `1/("P"_("total"))v//s" Y"_("B")` isnon linear

Solution :Plot of `1/("P"_("total"))" v"//"s"" Y"_("A")` is linear for an ideal BINARY mixture.
Discussion
18931.

The standard electrode potentials (E_(M^(+)//M)^(@)) of four metals A, B, C and D are -1.2V, 0.6V, 0.85 V and -0.76V, respectively. The sequence of deposition of metals on applying potential is

Answer»

B GT D gt C gt A
A gt C gt B gt D
C gt B gt D gt A
D gt A gt B gt C

Answer :C
Discussion
18932.

The substance that has the lowest boililng point is:

Answer»

`HCL`
`H_(2)S`
`PH_(3)`
`SiH_(4)`

Answer :D
Discussion
18933.

Which of the following stoichiometric laws suggests that different elements combine with each other by their equivalent weights ?

Answer»

LAW of definite proportion
Law of MULTIPLE proportion
Law of RECIPROCAL proportion
Law of CONSERVATION of mass

Answer :C
Discussion
18934.

ZSM-5 is used to convert :

Answer»

ALCOHOL to petrol
Benzene to toluene
Toluene to benzene
heptane to toluene

Answer :A
Discussion
18935.

Which one of the following alkali metals has lowest melting point ?

Answer»

Sodium
Potassium
Rubidium
Caesium

Solution :Potassium is alloyed with sodium in order to transfer heat in nuclear reactor . Their combination is denoted as NaK . Special precautions are required while using them as both are alkali METALS and may explode in CASE of exposure to AIR . Sodium is the most important metal for nuclear REACTIONS.
Discussion
18936.

What is the effect of increasing pH on K_2Cr_2O_7 solution?

Answer»

Solution :On INCREASING PH, orange colour of `K_2Cr_2O_7` solution changes to yellow DUE to the FOLLOWING reaction :
`Cr_2O_7^(2-) + 2OH^(-) rarr 2CrO_(4)^(2-) + H_(2)O`
Discussion
18937.

Write half cell reaction and E^o Value of(SHE) standard hydrogen electrode.

Answer»

SOLUTION : Labelled diagram of SHE, label - pt foil,`H_2(G) ` (1 bar),`MH downarrowH_(AQ)^+ +e^- to 1/2H_2(g), E^o =0.00V.`
Discussion
18938.

What is the amount of work done when 0.5 mole off methane, CH_(4)(g), is subjected to combustion at 300 K? (Given, R=8.314JK^(-1)mol^(-1))

Answer»

`-2494J`
`-4988J`
`+4988J`
`+2494J`

Solution :COMBUSTION of methane
`CH_(4)+2O_(2)(G)toCO_(2)(g)+2H_(2)O(g)`
`W=-pxxDeltaV=-nRT`
`=-(-0.5)xx8.314xx300=+2494J`
Discussion
18939.

Which of the following diagram correctly represent variation of pH of a solution of NH_(4)OH by addition of increasing quantity (volume in ml) of a known HCl solution?

Answer»




Solution :On adding HCl, pH of the solution will DECREASE SLOWLY INITIALLY, and sharply NEAR the equivalent point.
Discussion
18940.

Which of the following has the lowest electron affinity ?

Answer»

K
B
C
F

Answer :A
Discussion
18941.

Which acid can combine with tis own salt

Answer»

HI
HBr
HCl
HF

Answer :D
Discussion
18942.

Which of the following compounds can be used as antifreeze in automobile radiators?

Answer»

Methyl alcohol
Glycol
Nitrophenol
Ethyl alcohol

Solution :Glycol is USED as an antifreeze in AUTOMOBILE radiators since it is soluble in water and has a much HIGHER b.p. (472 K) than `H_(2)O`
Discussion
18943.

What is ionic conductivity ? It is dependent on which bases ?

Answer»

Solution :* Definition: When electrolytes are dissolved in water, they furnish their own IONS in the solution hence its conductivity also increases. The conductance of electricity by ions present in the SOLUTIONS is called electrolytic or ionic conductance. Water has very low conductivity `3.5xx10^(-5)" S "m^(-1)`.
* Ionic conductivity depends on : (i) the nature of the electrolyte added (ii) size of the ions produced and their SOLVATION (iii) the nature of the solvent and its viscosity (iv) concentration of the electrolyte (v) temperature : it increases with the increase of temperature.
* Passage of direct current (DC) though ionic solution over a prolonged PERIOD can lead to change in its composition due to electrochemical reactions.
Discussion
18944.

Titanium can be obtained in a state of high purity by

Answer»

VAN Arkel METHOD
Poling
Cupellation
Electrorefining

Solution :Van Arkel method
Discussion
18945.

Write IUPAC name of the following

Answer»


ANSWER :4-Methoxybenzenamine.
Discussion
18946.

Which one of the following is used as an insulator and making conveyor belts?

Answer»

TERYLENE
orlon
NEOPRENE
Buna-N

Solution :neoprene
Discussion
18947.

Which one of the following has a potential more than zero

Answer»

`Pt,(1)/(2)H_(2)(1atm)|HCl(1M)`
`Pt,(1)/(2)H_(2)(1atm)|HCl(2M)`
`Pt,(1)/(2)H_(2)(1atm)|HCl(0.1M)`
`Pt,(1)/(2)H_(2)(1atm)|HCl(0.5M)`

ANSWER :B
Discussion
18948.

The size of the trivalent cation in the lanthanoid series decreases steadily as the atomic number increases. What is this known as ?

Answer»

SOLUTION :LANTHANOID CONTRACTION.
Discussion
18949.

Which one is a synthetic polymer?

Answer»

Starch
Silk
Protein
Neoprene

Answer :D
Discussion
18950.

Whichamongthe followingis known assilman regent ?

Answer»

`R_(2)CULI`
Lil
Cul
Li

Answer :A
Discussion