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18001.

Why cannot Al be reduced by carbon ?

Answer»

Solution :Aluminium is STRONGER reducing AGENT than CARBON and therefore, cannot be REDUCED by it.
Discussion
18002.

Which of the following halides would undergo nucleophilic substitution most readily (SN_1)?

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1- Chloro-1 BUTANE
2 - Chloro -1- butane
3- Chloro -1- butene
4- Chloro -1- butene

Answer :C
Discussion
18003.

When H_2SO_4 is added to charcoal

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There is no reaction
Water GAS is FORMED
`SO_2 and CO_2` are EVOLVED
`CO and SO_2` are evolved

Answer :C
Discussion
18004.

What are active centres?

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Solution : (i) The surface of a catalyst is not SMOOTH. It bears steps, cracks and corners. (ii) Hence the atoms on such locations of the surface are co-ordinatively unsaturated. iii) So, they have much residual force of attraction. (iv) Such sites are CALLED active centres. So, the surface carries HIGH surface free ENERGY (v) The presence of such active centres increases the rate of REACTION by adsorbing and activating the reactants
Discussion
18005.

Two -OH bonds are present in

Answer»

<P>`H_(4)P_(2)O_(5)`
`H_(4)P_(2)O_(6)`
`H_(3)PO_(4)`
`H_(4)P_(2)O_(7)`

ANSWER :A
Discussion
18006.

The vapour pressure of two liquids X and Y are 80 and 60 torr respectively. The total vapour pressure of the ideal solution obtained by mixing 3 moles of X and 2 moles ofYwould be

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68 Torr
140 Torr
48 Torr
72 Torr

SOLUTION :According to given information
`p _(X) =80` Torr
`p _(Y) =60` Torr
`n _(X)=3` moles
`n_(X) =2` moles
`n _(Y)=2` moles
mole fraction of `X (x_(X))=(n _(X))/(n _(X)+ n_(Y))=(3)/(3+2) =3/5`
mole fraction of `Y (x _(Y))=(n_(X))/(n_(X)+ n _(Y)) =(2)/(3+2) =2/5`
Total Pressure, `P = p_(x) x _(X) + p_(Y) x _(Y)`
`=3/5x 80 +2/5 XX 60 =40+24=72.` Torr.
Discussion
18007.

Write Nernst equation for single electrode potential.

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Solution :For the ELECTRODE reaction, `M^(N+)//n e^(-)TOM`
`E_(M^(N+)//M)=E_(M^(n+)//M)^(@)-(2.303RT)/(nF)"log"([M])/([M^(n+)])=E_(Mn^(2+)//M)^(@)-(2.303RT)/(nF)"log"(1)/([M^(n+)])`.
Discussion
18008.

Which of the following acid does not contain +5 oxidation state ?

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Orthophosphoric acid
Pyrophosphoric acid
Phosphorus acid
Metaphosphoric acid

Answer :C
Discussion
18009.

Which of the following reactions will not give a primary amine?

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`CH_3 CONH_2 OVERSET(Br_2 // KOH)to`
`CH_3 CNoverset(LiAIH_4 )to`
`CH_3 NCoverset(LiAIH_4) to `
`CH_3 CONH_2 overset(LiAIH_4)to`

SOLUTION :`CH_3 NCoverset(LiAIH_4) to `
Discussion
18010.

What is the role of zinc metal in the extraction of silver ?

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Solution :Zinc is more electropositive than silver and it displaces silver from the SOLUBLE cyanide COMPLEX.
`2Na[Ag(CN)_(2)]+Zn to Na_(2)[Zn(CN)_(2)]+underset((ppt.))(2AG)`
Discussion
18011.

Which of the following solutions have lowest freezing point ?

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0.1 M glucose
0.1 M NaCl
0.1 M `BaCl_(2)`
0.1 M urea

Solution :`Delta T_(b)` will depend UPON the number of particles GIVEN by the solute in the solution (concentration is same).
(A) 0.1 M glucose (0.1 mole particles)
(B) 0.1 M NaCl (`NaCl hArr Na^(+)+Cl^(-),0.2` mole particles)
(C) `0.1 M BaCl_(2)(BaCl_(2) hArr Ba^(2+)+2Cl^(-), 0.3 "mole particles")`
(D) 0.1 M urea (0.1 mole particles).
`DeltaT_(b)` will be largest for C and , therefore, boiling point will be largest.
Discussion
18012.

Which is correct relation in between (dC)/dt,(dn)/dtand(dP)/dtwhere C,n,P, represents concentration ,mole and pressure terms for gaseous phase reactant A(g)rarr product.

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`-(DC)/dt=-1/V(DN)/dt=-1/(RT)(dP)/dt`
`(dC)/dt=(dn)/dt=-(dP)/dt`
`(dC)/dt=(RT)/V(dn)/dt=-(dP)dt`
All

Answer :A
Discussion
18013.

Urea is prepared in the laboratory by the action of NH_(3) on

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CARBONYL CHLORIDE ETHYL carbonate
cyanamide

Answer :A::B
Discussion
18014.

The size of particles in suspension, true solution and colloidal solution varies in the order :

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SUSPENSION`gt`COLLOIDAL`gt`true solution
true solution `gt` suspension `LT` colloidal
suspension `gt` colloidal solution = true solution
None of the above

Answer :A
Discussion
18015.

Why are solids hard and rigid ?

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SOLUTION :Due to strong ATTRACTIVE forces between the constituent UNITS.
Discussion
18016.

Which of the following is most reactive toward catalytic hydrogenation ?

Answer»

`R-OVERSET(O)overset(||)(C)-CL`
`R-C-=C-R`
`R-CH=CH-R`

ANSWER :A
Discussion
18017.

Which of the following are not aromatic?

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Solution :An aromatic compound MUST (i) be cyclic (ii) be planar (iii) contain each C - atom in `sp^(2)` hybridised state
(IV) should contain `(4n+2)pi` ELECTRONS.
Discussion
18018.

The standard reduction potentials for Zn^(2+)//Zn, Ni^(2+)//Ni and Fe^(2+)//Fe are -0.76,-0.23 and -0.44 V respectively. The reaction X+Y^(2+)toX^(2+)+Y will be spontaneous when

Answer»

`X=Zn,Y=Ni`
`X=Ni,Y=Fe`
`X=Ni,Y=Zn`
`X=Fe,Y=Zn`

SOLUTION :The reaction `X+Y^(2+)toX^(2+)+Y` will be SPONTANEOUS if `E_(CELL)^(@)` is +ve.
(a) `Zn+Ni^(2+)toZn^(2+)+Ni`,
`E_(cell)^(@)=E_(Ni^(2+)//Ni)^(@)-E_(Zn^(2+)//Zn)^(@)=-0.23-(-0.76)V`
(b) `Ni+Fe^(2+)toNi^(2+)+Fe,E_(cell)^(@)=E_(Fe^(2+)//Fe)^(@)-E_(Ni^(2+)//Ni)^(@)=-0.44-(-0.23)V`
`=-0.21V`
(c) `Ni+Zn^(2+)toNi^(2+)+Zn,E_(cell)^(@)=-0.53V` from (a)
(d) `Fe+Zn^(2+)toFe^(2+)+Zn,E_(cell)^(@)=E_(Zn^(2+)//Zn)^(@)=E_(Fe^(2+)//Fe)^(@)=-076-(-0.44)V=-0.32V`
Discussion
18019.

What are antiseptics ? Give examples.

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Solution :Drugs which are APPLIED to the living tissues to kill the bacteria and to stop their growth in wound, thus preventing its infection are called antiseptics. Examples : Iodoform, BORIC acid, phenol (DILUTE solution), `H_(2)O_(2)`, etc.
Discussion
18020.

Which compound is soluble in NH_(4)OH

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`PbCl_(2)`
`PbSO_(4)`
`AGCL`
`CaCO_(3)`

Answer :C
Discussion
18021.

Which of the following isomerism is/are not shown by the complex [Co(Cl_(2)(OH)_(2)(NH_(3))_(2)]Br?

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Ionization
Linkage
Gemetrical
Optical

Solution :`[CoCl_(2)(OH)_(2)(NH_(3))_(2)]Br`
ionisation, GEOMETRICAL, optical (CIS form)
Discussion
18022.

Which of the following reagents can be used to prepare ethyl carbylamine (as a major product) from ethyl iodide

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HCN
KCN
CuCN
AgCN

Answer :D
Discussion
18023.

Why alkyl cyanides are soluble in water?

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SOLUTION :LOWER alkyl cyanides are WATER soluble because they can FORM hydrogen BONDS with water.
Discussion
18024.

Which one of the following does not represent cell constant correctly ?

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It is the ratio of specific conductance to observed conductance
It is the ratio of distance between the electrodes to the area of cross-section of the electrode
It is the product of specific resistance and observed resistance
It is the product of conductivity and observed resistance .

SOLUTION :k = `G xx ` CELL constant `NE R xx` cell constant .
Discussion
18025.

Which combination (s) of alkyl bromide and epoxide can be used to prepare the following product by addition of the Grignard derived from the alkyl bromide to the epoxide ?

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SOLUTION :
Discussion
18026.

The time of completion of 90% of a first order reaction is approximately

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1.1 TIMES that of half-LIFE
2.2 times that of half-life
3.3 times that of half - life
4.4 times that of half-life

SOLUTION :For a first order reaction
`k = (2.303)/(t)"log" (a)/((a-x))`
` t = (2.303)/(k) "log" (100)/((100 - 90)) = (2.303 XX t_(1//2))/(0.593) xx "log" (100)/(10)`
`= 3.3 xx t_(1//2) xx "log" 10 = 3.3 t_(1//2)`.
Discussion
18027.

What happens when colloidal solution ofFe(OH)_(3) smf As_(2)S_(3) are mixed ?

Answer»
Discussion
18028.

Which of the following cannot act as Lewis acid?

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`BCl_(3)`
`SiCl_(4)`
`SiF_(4)`
`C Cl_(4)`.

Solution :`C Cl_(4)` cannot accept ELECTRONS because of the absence of d - orbitals.
Discussion
18029.

What will bethe initial rate of a reaction if its rate constant is 10^(-3) min^(-1) and the concentration of reactant is 0.2 mol dm^(-3) ? How much of reactant will be converted into Products in 200 min?

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SOLUTION :`2.0 xx 10^(-4) "mol" dm^(-3) "min"^(1), 18%`
Discussion
18030.

Which of the following can be used as the halide component for Friedel-Crafts reaction?

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Chlorobenzene
Bromobenzene
Chloroethene
Isopropyl chloride

Solution :ARYL halides (i.e., chlorobenzene and bromobenzene) and vinyl halides (i.e., chloroethane) being LESS REACTIVE (than alkyl halides) do not react with benzene to GIVE the corresponding substitution products. Therefore, only isopropyl chloride can be used as the halide component in F.C. reactions.
Discussion
18031.

Which of the following molecules possess a plane of symmetry ?

Answer»




More than ONE of these

Answer :B
Discussion
18032.

Write Freundlich's adsorption isotherm.

Answer»

<P>

Solution :`x/m = kp^(1//N)` ,where `x/m`represents extent of adsorption, p is PRESSURE, k is constant and n is a whole NUMBER.
Discussion
18033.

The solubility of oxygen in water is 1.25xx10^(-3) M at a pressure of 1 atm and 298 K . Solubility of atmospheric oxygen at sea level and the same temp will be :

Answer»

`1.25 xx10^(-3)M`
`2.5 xx10^(-3)M`
`2.5xx10^(-4)M`
`1.00xx10^(-3)M`

ANSWER :A
Discussion
18034.

Which of the following ion posses six unpaired electrons ?

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`Eu^(3+), Ce ^(3+), GD^(3+)`
`Eu^(3+), Tb ^(3+), SM ^(2+)`
`Tb ^(3+), Nd ^(3+), Sm ^(2+)`
`Sm ^(2+) , Er ^(3+) , Eu ^(2+)`

Answer :B
Discussion
18035.

Yb^(+2) and Lu^(3+)are diamagnetic due to

Answer»

VACANT 'f' sub SHELLS
Fully 'f' sub shells
Partly filled 'f' sub shells
Partly filled 'd' sub shells

Answer :B
Discussion
18036.

Which one of these is not known?

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`CuCl_(2)`
`CuI_(2)`
`CuF_(2)`
`CuBr_(2)`

Solution :All FOUR copper (II) halides are known except cupric iodide `(CUI_(2))` which rapidly decomposes to cuprous iodide, `Cu_(2)I_(2)` and `I_(2)`
`2CuI_(2) RARR Cu_(2)I_(2)+I_(2)`
Discussion
18037.

What would be the partial pressure of oxygen gas to get equal moles of SO_2 and SO_32SO_2(g) + O_2(g) iff 2SO_3(g)Given that partial pressures of SO_2, O_2and SO_2are 0.662 atm, 0.101 atm and 0.331 atm respectively.

Answer»

SOLUTION :0.404 ATM
Discussion
18038.

Variability in the oxidation states of lanthanides is limited. Why?

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Solution :The COMMON oxidation state of lanthanides is `+3`. EXISTENCE of `+2 and +4` states is due to the fact that empty, half-filled or completely f-subshells provide lower energy and ions get stabilised. `Ce^(4+)` has `f^(0), Tb^(4+)` ha `f^(7), Eu^(2+)` has `Yb^(2+)` has `f^(14)` stable configurations.
Discussion
18039.

What is epimerisation?

Answer»

Solution :The process by which ONE EPIMER is converted into other is called epimerisation and it requires the enzymes epimerase. Galactose is converted to GLUCOSE by this MANNER in our BODY.
Discussion
18040.

What is the effect of the following groups on the acidity of phenol ? (i) -CH_(3) group (ii) -NO_(2) group.

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Solution :(i) The PRESENCE of `-CH_(3)`group in the phenol decreases the acidity of phenol as it is an ELECTRON donatinggroup. Therefore, it will INTENSIFY the NEGATIVE charge and thus, release of a proton becomes more difficult.As a result, the acidity decreases.
(ii) Since - `NO_(2)`group is an electron withdrawing group. It disperses, the negative charge of the phenonide ion and thus STABILIZES it. Therefore, `NO_(2)`group will increase the acidic strength of phenols.
Discussion
18041.

Which of the following is more basic than aniline? .

Answer»

Diphenylamine
Triphenylamine
p - nitroaniline
Benzylamine

Answer :D
Discussion
18042.

What happens to the entropy of a gas after adsorption?

Answer»

SOLUTION :DECREASES
Discussion
18043.

Time required to decompose SO_(2)Cl_(2) to half of its initial amount is 60 minutes .If the decomposition is a first order reaction.Calculate the rate constant of the reaction.

Answer»

SOLUTION :0.01155 `MIN^(-1)`
Discussion
18044.

Which one of the following species is planar and non-polar with two lone pairs of electrons on the central atom ?

Answer»

`CIF_3`
`XeF_5^(-)`
`PCl_5`
`BrF_5`

SOLUTION :
Discussion
18045.

When H^+ is going to be added to the PO_5^(3–), then the obtained formula will not have the structure of

Answer»




ANSWER :A::C::D
Discussion
18046.

Which one of the following contains particle equalto those in 12 g Mg ?( AT.WT. Mg = 24)

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12 G carbon
7 g nitrogen
32 g oxygen
24 g carbon

Answer :B
Discussion
18047.

What is the action of ammonia on the following : (a) Br_(2) (b) I_(2)(c) Na (d) Cu^(2+) (e ) CoCl_(2) ?

Answer»

Solution :(a) `NH_(3)`, with `Br_(2)`, forms `NH_(4)Br` and `N_(2)`
`8NH_(3) + 3Br _(2) to 6NH_(4)Br + N_(2)`
(b) Ammonia with `I_(2)` forms brown PRECIPITATE of nitrogen triodide ammonia, `NH_(3)NI_(3)`
`2NH_(3) + 3I_(2) to NH_(3) NI_(2) +3HI`
`NH_(3) NI_(2)` is explosive in dry state and decomposes to produce `N_(2)` and `I_(2)`
`8NH_(3)NI_(3) to 5N_(2) + 9I_(2) + 6NH_(4)I`
(c) Ammonia with electropositive metal like Na and K forms amide.
`2Na +2NH_(3) to underset("deep BLUE COMPLEX")([Cu(NH_(3))_(4)]_((aq)))`
(d) `Cu_((aq))^(2+) + 4NH_(3)^((aq)) to underset("deep blue complex")([Cu(NH_(3))_(4)]_((aq)))`
(e) `CoCl_(2) + 6NH_(3) to [Co(NH_(3))_(6)]Cl_(2)`
Discussion
18048.

Which of the following methods can not be used to determine the molecular weight of non-volatile solute?

Answer»

VICTOR Meyer.s METHOD
OSMOTICPRESSURE method
Cryoscopic method
Ebullioscopic method

Answer :A
Discussion
18049.

Which of the following complex (Werner presentation) have minimum electrical conductance in aqueous solution

Answer»




ANSWER :D
Discussion
18050.

The vapour pressures of pure liquids A and B are 450 and 700 mm Hg at 350 K respectively. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Answer»

Solution :Here, `p_(A)^(@)="450 mm,"p_(B)^(@)="700 mm,"p_("Total")="600 mm"`
`"Applying Raoult's law,"p_(A)=x_(A)xxp_(A)^(@),""p_(B)=x_(B)xxp_(B)^(@)=(1-x_(A))p_(B)^(@)`
`""P_("Total")=p_(A)+p_(B)=x_(A)p_(A)^(@)+(1-x_(A))p_(B)^(@)=p_(B)^(@)+(p_(A)^(@)-p_(B)^(@))x_(A)`
Substituting the GIVEN values, we get
`600=700+(450-700)x_(A)"or"250x_(A)=100"or"x_(A)=(100)/(250)=0.40`
THUS, composition of the liquid mixture will be
`x_(A)" (mole fraction of A) = 0.40,"x_(B)" (mole fractiobn of B)"=1-0.40=0.60`
`THEREFORE""p_(A)=x_(A)xxp_(A)^(@)=0.40xx"450 mm = 180 mm,"p_(B)=x_(B)xxp_(B)^(@)=0.60xx"700 mm = 420 mm"`
`"Mole fraction of A in the vapour phase"=(p_(A))/(p_(A)+p_(B))=(180)/(180+420)=0.30`
Mole fraction of B in the vapour phaes `=1-0.30 = 0.70.`
Discussion