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3951.

Which of the following conditions regarding a chemical process ensures its spontaneity at all temperature

Answer»

`DeltaH gt 0, DeltaS LT O`
`DeltaH lt 0, DeltaS gt O`
`DeltaH lt 0, DeltaS lt O`
`DeltaH gt 0, DeltaS lt O`

SOLUTION :For SPONTANEITY `Delta lt 0` , which is possible when `DeltaH lt 0, DeltaS gt 0.`
Discussion
3952.

What scheme of hybridisation is proposed for Co in [Co(NH_(3))_(6)]^(3+) ?

Answer»

SOLUTION :`d^(2)SP^(3)` HYBRIDISATION.
Discussion
3953.

Which of the following is one of the products formed when NH_(3) reacts with NaOCl ?

Answer»

`NH_(2)NH_(2)`
NaOH
`Cl_(2)`
`NH_(4)CL`

Answer :A
Discussion
3954.

The solution of sodium carbonate has pH

Answer»

Greater than 7
Less than 7
Equal to 7
Equal to zero

Solution :`Na_(2)CO_(3)` is a mixture of weak ACID and strong BASE, so it is a base.
Discussion
3955.

What happens when CH_(3)-Br is treated with KCN?

Answer»

Solution :Ethanenitrile or Acetonitrile is formed.
`UNDERSET("Ethyl chloride")(CH_(3)CH_(2)-Cl)KOH(aq)to underset("Ethyl alcohols")(CH_(3)CH_(2)-OH)+KCl`
Discussion
3956.

The second ionisation energy of the following elements follows the order

Answer»

`ZN gt Cd lt HG`
`Zn gt Cd gt Hg`
`Cd gt Hg lt Zn`
`Zn lt Cd lt Hg`

ANSWER :A
Discussion
3957.

Total number of lone pairs of electron in melamine is

Answer»


Solution :SIX . Each N has a PAIR of electrons. SINCE there are six N atoms so there are six lone pairs of electrons.
Discussion
3958.

Which of the following is a good conductor of electricity?

Answer»

Diamond
Graphite
Solid NaCl
Wood

Answer :B
Discussion
3959.

Write the disproportionation reaction of H_(3)PO_(3).

Answer»

SOLUTION :`4H_(3)PO_(3) to 3H_(3)PO_(4)+PH_(3)`
Discussion
3960.

What are antimicrobials ?

Answer»

SOLUTION :These are the chemical SUBSTANCES USED to cure INFECTIONS DUE to micro-organisms.
Discussion
3961.

Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH_(2)CONH_(2)) is dissolved in 850 g of water. Calculate the vapour pressure of water of this solution and its relative lowering.

Answer»

<P>

Solution :Here,`""p^(@)="23.8 mm"`
`""w_(2)=50g,""M_(2)"(urea) = 60 G mol"^(-1),""w_(1)=850 g, M_(1)" (water) = 18 g mol"^(-1)`
Our aim is to calculate `p_(s) and (p^(@)-p_(s))//p^(@)`
`"Applying Raoult's law."=(p^(@)p_(s))/(p^(@))=(n_(2))/(n_(1)+n_(2))= (w_(2)//M_(2))/(w_(1)//M_(1) +w_(2)//M_(2)) =(50//60)/(850//18+50//60)`
`=(0.83)/(47.22+0.83)=(0.83)/(48.05)=0.17`
THUS, RELATIVE lowering of vapour pressure = 0.017
SUBSTITUTING `p^(@)=23.8` mm, we get
`(23.8-p_(s))/(p^(@))=0.017 or(23.8-p_(s))/(23.8)=0.017or23.8-p_(s)=0.017 xx23.8=0.40`
`"or"p_(s)=23.8-0.40="23.4 mm"`
Thus, vapour pressure of water in the solution = 23.4 mm.
Discussion
3962.

Which option is not applicable to physical adsorption ?

Answer»

It is INSTANTANEOUS. 
It is IRREVERSIBLE. 
Multi-molecular LAYERS are formed in it.
The value of `E_(a)` is COMPARATIVELY low.

Solution :It is irreversible.
Discussion
3963.

Write short notes on the following Ammonolysis

Answer»

Solution :When Alkyl halides (or) benzylhalides are heated with alcoholic ammonia in a sealed tune, mixutres of `1^(@),2^(@)" and "3^(@)` amines and quaternary ammonium salts are obtained.
`{:(CH_3-Br underset(triangle)overset(ddotNH_3)(to)CH_3-ddotNH_2overset(CH_3-Br)(to)(CH_3)_2ddotNH overset (CH_3Br)(to)(CH_3)_3ddotN overset(CH_3Br)(to)(CH_3)_4overset(+)(N) Bbarr),(""1^(@)- " amine """2^(@)- " amine """ 3^(@) - " amine "" "" Quarternary ammonium bromide "):}`
This is a nucleophilic substitution, the HALIDE ion of alkly halide is substituted by the `-NH_2` group. The product primary amine so formed can also has a tendency to act as a nucleophile end hence if excess alkyl halide is TAKEN, further nucleophilic substitution takes place leading to the formation of quarternary ammonium salt. However, if the process is carried out with excess ammonia, primary amine is abtained as the major product. The order of reactivity of alkylhalides with amines.
`RI gt RBr gt RCI`.
Discussion
3964.

Which oxidizing agent, O_2, O_3 or H_2O_2 ,will generate the greatest amount of energy for 1 mole of H_2(g)?(i) 2H_2(g) + O_2(g) to2H_2O(g),Delta H=- 483.6 kJ(ii) 3H_2(g) + O_2(g)to3H_2O(g), DeltaH =-868.2 kJ(iii) H_2(g) + H_2O_2(g)to2H_2O(g), Delta H =- 347.3 kJWhich of the above given reactions will generate the greatest amount of energy on a total mass basis of reactants that may be used in rocket propulsion?

Answer»

Solution :` H_2(G) + H_2O_2(g)to2H_2O(g), Delta H =- 347.3 KJ`
`3H_2(g) + O_2(g)to3H_2O(g), DELTAH =-868.2 kJ `
Discussion
3965.

Which of the following complex shows geometrical isomerism?

Answer»

`[Zn(H_(2)O)_(2)Cl_(2)]`
`[CO(en)_(3)]^(3+)`
`[Co(en)Cl_(4)]^(-)`
`[Co(en)_(2)Cl_(2)]^(+)`

Solution :`(M"AA")_(2)a_(2)` showG.I.
Discussion
3966.

Which of these species has a standard enthalpy of formation equal to zero ?

Answer»

`F_(2)(G)`
F(g)
HF(aq)
`F^(-)(aq)`

Answer :A
Discussion
3967.

Which of the following reactions will give tetra methyl hydrazine ?

Answer»

`NH_(2)-NH_(2)+CH_(2)Cl_(2)`
`NH_(2)OVERSET(+)(N)H_(3)Cl+CH_(4)`
`(CH_(3))_(2)NH+H_(2)S_(2)O_(5)`
`(CH_(3))_(2)NH+KMnO_(4)`.

Solution :`2(CH_(3))_(2)NH UNDERSET(KMnO_(4))overset([O])(RARR) (CH_(3))_(2) underset("Tetramethylhydrazine")(N-N(CH_(3))_(2))+H_(2)O`
Discussion
3968.

Which of the following pairs is true for the process C_(6)H_(6)(g)[1atm,80.1""^(@)C]toC_(6)H_(6)(l)[1atm,80.1^(@)C]-

Answer»

`DeltaG LT 0,DELTAS GT0`
`DeltaG lt 0,DeltaS lt0`
`DeltaG=0,DeltaS lt0`
`DeltaG=0,DeltaS gt0`

Answer :C
Discussion
3969.

Which of the following possible (including by product) in above elimination reaction?

Answer»



`CH_(2)=CH_(2)`

ANSWER :A::B::C::D
Discussion
3970.

What is the sum of bond order of Fe-C bond and C-O bond in Fe(CO)_(5) ?

Answer»


ANSWER :4
Discussion
3971.

What may be the stable oxidation state of the transition element with the following d-electron configurations in the ground state of their atoms : 3d^(3),3d^(5),3d^(8) and 3d^(4) ?

Answer»

Solution :`3D^(3)4S^(2)=+5""3d^(5)4s^(1)=+6`
`3d^(5)4s^(2)=+2,+7""3d^(8)4s^(2)=+2`
`3d^(4)4s^(2)` or `3d^(5)4s^(1)=+3` and +6
Discussion
3972.

Which of the following compound do not have white colour in the formof ppt ?

Answer»

`Bi_(2)S_(3)`
`Co[Hg(SCN)_(4)]`
`CdS`
`BiI_(3)`

Answer :a,b,c,d
Discussion
3973.

Which Polymer is a cross-linked Polymer ?

Answer»

BAKELITE
DACRON
TEFLON
ORLON

SOLUTION :Bakelite
Discussion
3974.

The substance not likely to contain CaCO_(3) is :

Answer»

dolomite
a MARBLE STATUE
CALCINED gypsum
sea shells

Answer :C
Discussion
3975.

The swelling of a gel in water is called……….

Answer»

SOLUTION :IMBIBITION
Discussion
3976.

Which one of the following organohalogen compounds when heated with alcoholic potassium hydroxide does not undergo dehydrohalogenation reaction?

Answer»

SECONDARY BUTYL chloride.
Isopropyl chloride.
Neopentyl chloride.
Isobutyl chloride

Solution :Neopentyl chloride is tertiary in NATURE.
It has no `BETA`-hydrogen ATOM. As a result, it does underg dehydrohalogenation reaction.
Discussion
3977.

Which is the monomer of polystyrene ?

Answer»

`C_(2)H_(5)-CH=CH_(2)`
`CH_(2) = CHCI`
`C_(6)H_(5) - CH = CH_(2)`
`CH_(2) = CH – CHO`

Solution :`C_(6)H_(5) - CH = CH_(2)`
Discussion
3978.

BOND ENTHALPY

Answer»

Solution :Bond enthalpy (or Bond energy) : The enthalpy change or amount of HEAT energy required to break one MOLE of particular covalent bonds of gaseous molecules FORMING free gaseous atoms or RADICALS at constant temperature (298 K) and pressure (1 atmosphere) is called bond enthalpy or bond energy.
For example bond enthalpy of `H_(2)` is `436.4"k J mol"^(-1)`. It is denoted by, `Delta H^(@)=346.4" kJ mol"^(-1) or D_(H_(2))=436.4" kJ mol"^(-1)`.
Discussion
3979.

The standard reaction potential of a calomel half cell is 0.28V at 25^@C. Calculate half cell potential when 0.1N KCl solution is used

Answer»

Solution :`Hg_2Cl_2 (s)+2e^(-) to 2HG + 2CL^(-) (0.1 N KCl)]`(0.339 V)
Discussion
3980.

What is roasting?

Answer»

Solution :The process of heating an ORE (generally,SULPHIDE ore) is strongly below its melting point in the presence of an excess of air is CALLED roasting
Discussion
3981.

Which is not a laboratory test for 1^(@) amides ?

Answer»

`CHCl_(3)+KOH`
`CS_(2)+HgCl_(2)`
Dil.`NaOH,DELTA`
LITMUS test

Solution :N//A
Discussion
3982.

Which behaves both as a nucleophile and electrophile

Answer»

`CH_(3)NH_(2)`
`CH_(3)Cl`
`CH_(3)CN`
`CH_(3)OH`

SOLUTION :`CH_(3)CN` behaves both as nucleophile and electrophile.
Discussion
3983.

What will be the molality of the solution containing 18.25 g of HCl gas in 500 g of water ?

Answer»

0.1 m
1 M
0.5 m
1 m

Solution :`"MOLALITY"=("Moles of the SOLUTE")/("MASS of the solvent in KG")=(18.25//36.50)/(0.500kg)=1m.`
Discussion
3984.

What is ultrasonic dispersion?

Answer»

SOLUTION :Sound waves of frequency more than 20kHz (AUDIBLE limit) COULD cause transformation of course SUSPENSION to colloidal dimensions.
Discussion
3985.

Which of the following statements are correct about azetopic mixture ?

Answer»

It is a constant boiling mixture
Componts connot be SEPARATED by fractionl distilltions
An azetropic mixture of water-alcohol CONTAINS only 4.4% water by mass
A liquid PAIR which shows positive deviation form Raoult's law may BEHAVE as a minimum boiling azeotropr.

Solution :(a,b,C,d) are all correct.
Discussion
3986.

Which alkyl halide from the following pairs would you expect to react more rapidly by an S_(N)2 mechanism? Explain your answer. (iii) CH_(3)underset(CH_(3))underset(|)(C)HCH_(2)CH_(2)Br or CH_(3)CH_(2)underset(CH_3)underset(|)(C)HCH_(2)Br.

Answer»

Solution :Out of the two isomeric `1^(@)` alkyl bromides, the FORMER has a methyl groups on the `delta` -CARBON while the LATTER has a methyl GROUP on the `beta`- carbon. As a result, `alpha`- carbon of the former compound. So, 3-methyl - 1- bromobutance reacts more rapidly by `S_(N)2` mechanism.
Discussion
3987.

Which of the following compounds would undergo cannizzaro reaction ? Benzaldehyde, Cyclohexanone , 2-mehtylpentanal.

Answer»


SOLUTION :BENZALDEHYDE
Discussion
3988.

using following data H_(2)O(l)[373.15K , 1 atm ] to H_(2)O(g)[ 373.15 K , 1 atm], DeltaS_(1) H_(2)O(s) [ 273 .15 K, 1 atm] to H_(2)O(l)[273.15 K,1 atm], DeltaS_(2) predict which of the following is correct ?

Answer»

`DeltaS_(1)=DeltaS_(2)`
`DeltaS_(1)gtDeltaS_(2)`
`DeltaS_(1)ltDeltaS_(2)`
`DeltaS_(1)` may be greater or SMALLER than `DeltaS_(2)`

SOLUTION :Vaporisation of water CREATES more creates more randomness. HENCE , has more entropy.
Discussion
3989.

Which metal is mainly present in the impure form in Cu obtained by Bessemerisation process ?

Answer»

S 
Fe
Pt 
(A) and (B) 

ANSWER :D
Discussion
3990.

Which of the following statements is incorrect about a solution ?

Answer»

A solution is always a homogeneous mixture.
The solute particles in a solution have size LESS than 10 A.
Brass CONNOT be CALLED a solution.
An ionic compound dissolves in water if the hydration ENERGY is greater than lattice energy.

Solution :Brass is a solution of solid in solid (Cu+Zn).
Discussion
3991.

Which one is not a state function:

Answer»

INTERNAL ENERGY(U)
Volume
Heat (Q)
Enthalpy

Answer :C
Discussion
3992.

When a lead storage battery is charged?

Answer»

`PbO_(2)` dissolves
The LEAD ELECTRODE becomes COATED with lead sulphate
Sulphuric ACID is regenerated
The AMOUNT of acid decreases

Answer :C
Discussion
3993.

Which of the products will be major product in the reaction given below ? Explain.CH_(3)CH=CH_(2)+HI to underset((A))(CH_(3)CH_(2)CH_(2)I)+underset((B))(CH_(3)CHICH_(3))

Answer»

Solution :According to Markovnikov.s Rule, (B) will be the major PRODUCT. The electronegative part of the reagent IUS added to carbon of double bond with least number of HYDROGENS.
Discussion
3994.

Which statement about electrolytic solution is incorrect -

Answer»

it provides surface for REDOX reacion
CONDUCTIVITY depends UPON VISCOSITY of solution
conductivity does not depend upon SOLVATION of ions
conductivity of solution increases with temperature

Answer :C
Discussion
3995.

Which of the following statements is in accordance with the Arrhenius equations?

Answer»

Rate of a REACTION INCREASES with increases in temperatures
Rate of reaction does not change with INCREASE in activation energy.
Rate constant decreases exponentially with increase in temperature.
Rate of reaction increases with decreases in activation energy.

Solution :d) Both these statements are correct. Rate of a reaction increases with the increase in temperature as well as DECREASE in activation energy.
Discussion
3996.

Whichone of the followingis formed when glucosereactwith Conc. HNO_(3) ?

Answer»

GLUCONIC ACID
Glutaricacid
Saccharic acid
Hexanoic aicd

Answer :C
Discussion
3997.

Which of the following is halogen exchange reaction ?

Answer»

`RX+NaI RARR RI+NaX`

`R-OH+HX OVERSET(ZnCl_(2))rarr R-X+H_(2)O`

ANSWER :A
Discussion
3998.

What is the experimental value of magnetic moment of metal ion in [Fe(CN)_(6)]^(4-)?

Answer»

4.90BM
5.00BM
0.00BM
5.92BM

Answer :C
Discussion
3999.

Write the mechanism of acid dehydration of ethanol of yield ethene. (ii) Write note on Reimer - Tiemann reaction.

Answer»

SOLUTION :`H_(2)SO_(4)hArr H^(+)+HSO_(4)^(-)`

(ii) Reimer - Tiemann REACTION. Treatment of phenol with chloroform in the PRESENCE of alkali to give salicylaldehyde is called Reimer - Tiemann reaction.
Discussion
4000.

Write IUPAC name of the complex (i) Na_(3)[Cr(OH)_(2)F_(4)](ii) [Cr(H_(2)O)_(5)Cl]Cl_(2)

Answer»

SOLUTION :(i) SODIUM tetrafluoridodihydroxochromate (III) (II) pentaaquachloridochromium (III) CHLORIDE.
Discussion