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7701.

Which of the following compounds on hydrolysis with aqueous alkali give a product which does not give positive iodoform reaction but gives positive silver mirror test. The compound is

Answer»




Solution :HYDROLYSIS does give positive SILVER TEST give silver mirror test but not IODOFORM test
Discussion
7702.

Which of the following is used as a catalyst in the manufacture of sulphuric acid form SO_(3)

Answer»

`V_(2)O_(5)`
Rh-Ir
Ni
Fe

Solution :`V_(2)O_(5)`
Discussion
7703.

What is the van't Hoff factor of a completely ionised aqueous solution of (i) NaCl (ii) KCl (iii) MgSO_(4) (iv) K_(2)SO_(4).

Answer»

Solution :(i) `NaCl to Na^(+)+CL^(-)`
`i=(2)/(1)=2`
(ii) `MgSO_(4) to Mg^(2+)+SO_(4)^(2-)`
`i=(2)/(1)=2`
(III) `KCl to K^(+)+Cl^(-)`.
`i=(2)/(1)=2`
(iii) `KCl to K^(+)+Cl^(-)`
`i=(2)/(1)=2`
(IV) `K_(2)SO_(4)to2K^(+)+SO_(4)^(2-)`
`i=(3)/(1)=3`.
Discussion
7704.

Which one does not give cannizzaro's reaction

Answer»

Benzaldehyde
2-methyl propanal
p-methoxy benzaldehyde
2,2-dimethyl propanal

SOLUTION :ALDEHYDE, which does not have the `alpha-H` atoms, gives Cannizzaro's reaction on heating with conc. Alkali solution (50%)

`underset(alpha-H-"atom absent")(CH_(3)OVERSET(CH_(3))overset(|)underset(CH_(3))underset(|)(C)-CHO)underset(alpha-H-"atom absent")(HCHO)`
Discussion
7705.

Thionyl chloride can be synthesised by chlorinating SO_2 using PCl_5. Thionyl chloride is used to prepare anhydrous ferric chloride starting from its hexahydrated salt. Alternatively, the anhydrous ferric chloride can also be prepared from its hexahydrated salt by treating with 2,2-dimethoxypropane. Discuss all this using balanced chemical equations.

Answer»

SOLUTION :Thionyl CHLORIDE is `SOCl_2`
`SO_2+PCl_5toSOCl_2+POCl_3`
`FeCl_3.6H_2O+6SOCl_2toFeCl_3+12KCl+6SO_2`
`FeCl_3.6H_2O+6CH_3C(OCH_3)_2CH_3toFeCl_3+13CH_3OH+6CH_3COCH_3`
Discussion
7706.

To prepare a pure sample of n-hexane, the ethernal solution of any of the following substance is treated with sodium. The correct substance is

Answer»

n-penthyl bromide and methyl bromide
n-propyl bromide
ethyl idodide and n-butyl iodide
all of these

Solution :In other cases, we hve also other hydrocarbos ALONG with hexane is CASE (b) only hexane is FORMED.
`2CH_(3)CH_(2)CH_(2)Br+2Na overset("dry ether") to C_(6)H_(14) +2NaBr`
Discussion
7707.

What is a flux? What is the role of flux in the metallurgy of iron and copper?

Answer»

Solution :Flux is a substance which COMBINES with gangue in the ORE to form SLAG. Slag seprates more easily from the ore than the gangue. Removal of gangue thus becomes easier. The ore is HEATED in a reverberatory furnace after mixing with silica. Iron oxide slags of as iron silicate and copper is produced in the form of copper matte. This contains `Cu_(2)S" and "FeS`.
`{:(FeO+SiO_(2) to FeSiO_(3)),("Slag"):}`.
Discussion
7708.

The vapour pressure of ethanol and methanol are 42.0 mm and 88.55 mm Hg respectively. An ideal solution is formed at the same temperature by mixing 46.0gof ethanol with 16.0of methanol. The mole fraction of methanol in the vapour is

Answer»

0.502
0.556
0.467
0.513

Answer :D
Discussion
7709.

Which of the following staements is wrong i) Shape of a aliphatie amines is pyrmidal ii) All amines are Bronsted bases iii) All primary amines exhibit functional isomerism iv) All tertiary amines shows functional isomerism

Answer»

i, II, III, iv
i & ii
i only
iii only

Answer :D
Discussion
7710.

Which of the following will produce a white precipitate upon reacting with AgNO_(3)?

Answer»

`[Co(NH_(3))_(6)]Cl_(3)`
`[Co(NH_(3))_(3)Cl_(3)]`
`K_(2)[PT(en)_(2)Cl_(2)]`
`[FE(en)_(3)]Cl_(3)`

SOLUTION :Only (a) and (d) have ionsisable `CL^(-)`
Discussion
7711.

To measure accurage cell potential of electrode of electrochemical cell, which instrument is used ?

Answer»

Galvanometer
Ammeter
POTENTIOMETER
voltmeter

Solution :Potentiometer
ACCURATE measurement of electrode can be DONE by potentiometer.
Discussion
7712.

What are Lewis acids and bases? Give two example for each.

Answer»

Solution :(i) Lewis acid is a species thataccepts an electron pair.
(ii) Lewis acid is a positive ione (or)an electron deficient molecule.
(iii) EXAMPEL, `Fe^(2+),CO_(2), BF_(3),SiF_(4)` ETC….
(i) Lewis acid is a species that donates an electron pair.
(ii) Lewis acid is an ANION (or) neutral molecule with atlesat one lone pair of electrons.
(iii)Example, `NH_(3),F^(-),CH_(2)=CH_(2),CaO` etc...
Discussion
7713.

Which compound does not give NH_3 on heating ?

Answer»

`(NH_4)_2SO_4`
`(NH_4)_2CO_3`
`NH_4NO_2`
`NH_4Cl`

ANSWER :C
Discussion
7714.

Which of the following is a trisaccharide?

Answer»

Stachyose
Sucrose
RAFFINOSE
RIBOSE

Solution :On hydrolysis is stachyrose gives four, sucrose gives two, raffinose gives THREE and ribose gives no MOLECULES, of monosaccharides. Thus, only raffinose is a trisaccharide.
`C_18H_32O_16 + H_2O to 3C_6H_12O_6`
Discussion
7715.

When 2-butyne is brominated, A is formed . When 2-butyne is reacted with HgSO_4 and H_2SO_4 , then B is formed which then gives C . Hence

Answer»



B is `Me-undersetunderset(OH)|C=CH-Me` and C is `Me-oversetoverset(O)(||)C-CH_2-CH_3`
B is `Me-undersetunderset(OH)|oversetoverset(OH)|C=CH-Me` and C is `Me-oversetoverset(O)(||)C-CH_2-CH_3`

SOLUTION :
Discussion
7716.

What are the different oxidation states exhibited by Lanthanoids?

Answer»

SOLUTION : + 3, +2, + 4.
Discussion
7717.

What happened when CH_(3)- underset(OH)underset(|)CH-CH_(3) undergo Lucas Test?

Answer»

Mixture remain unreacted
Mixture becomes milky WHITE within 5 minutes
Oily DROPLETS OBSERVED on the surface
Mixture becomes BROWN coloured

Solution :Mixture becomes milky white within 5 minutes
Discussion
7718.

Write the structures of A and B in the following reaction CH_(3)MgBr underset((ii)H_(3)O^(+))overset((i)CO_(2))to A overset(PCl_(5))toB

Answer»

SOLUTION :`underset("Methylmag. Bromide")(CH_(3)MgBr) overset(CO_(2)) to [CH_(3)-overset(O)overset(||)(C)-OMgBr] underset(-Mg(OH)Br)overset(H_(3)O^(+))to underset("Acetic acid (A)")(CH_(3)-overset(O)overset(||)(C)-OH) underset(-POCl_(3)-HCl) overset(PCl_(5))to underset("Acethyl chloride (B)")(CH_(3)-overset(O)overset(||)(C)-CL)`
Discussion
7719.

Which one of the following speciesacts as both Bronsted acid and base ?

Answer»

`H_(2)PO_(2)^(-)`
`HPO_(3)^(2-)`
`HPO_(4)^(2-)`
All of these

Solution :`HPO_(4)^(2-) +H_(2)O IFF H_(2)PO_(4)^(-) +OH^(-)`
`HPO_(4)^(2-)+H_(2)O iff PO_(4)^(3-) +H_(3)O^(+)`
`H_(3)PO_(2)^(-)` is a conjugate BASE of `H_3PO_(2)` ( a monobasic acid ) and does not give `H^(+),HPO_(3)^(2-)` is conjugate base of `H_2PO_(3)^(-)` and does not ionise further , since `H_(3)PO_(3)` is a dibasic acid .
Discussion
7720.

What is catalyst?What is inhibitor?

Answer»

SOLUTION :CATALYST:A catalyst is a substance which increase the rate of reaction without itself UNDERGOING any permanent chemical change.e.g. `MnO_(2)` catalyses the following reaction so as to increase its rate considerably .
`2KClO_(3)overset(MnO_(2))to2KCl+3O_(2)`
INHIBITOR:When the added substance reduces the rate of reaction is called inihibitor .The word catalyst should not be used for inhibitor.
Discussion
7721.

Which will have greater molar conductivity and why? Sol.(A) 1 mol KCl dissolved in 200 cc of the solution. Sol.(B) 1 mol KCl dissolved in 500 cc of the solution.

Answer»

Solution :Sol. (B) will have greater molar CONDUCTIVITY because
`lambda_m = k xx V`
with dilution k DECREASES but V increases, so that product will INCREASE more.
Discussion
7722.

Which of the following is not an alpha-amino acid ?

Answer»

SERINE
ASPARTIC ACID
PHENYLALANINE
Thymine.

Solution :Thymine is not an `alpha`-amino acid.
Discussion
7723.

Which one is broadspectrum antibiotic ?

Answer»

Chloramphenicol
Plamoquine
Xylocaine
ANTISEPTIC

ANSWER :A
Discussion
7724.

When HCl gas is passed through saturated solution of BaCl_(2), a white ppt. is obtained. This is due to

Answer»

Impurities in `BaCl_(2)`
Impurities in HCl
Precipitation of `BaCl_(2)`
Formation of complex

Solution :White precipitate obtained is of `BaCl_(2)`, as the `CL^(-)` ion concentration INCREASES due to the ADDITION of HCl, the ionic product becomes more than solublity product and thus, `BaCl_(2)` is precipitated.
Discussion
7725.

What will be the same in the isotonic solution at same temperasture ?

Answer»

SIZE
N
M
Mole FRACTION

ANSWER :C::D
Discussion
7726.

Which among the followingequations represents the reductionreaction taking place in lead accumulatorat positiveelectrode,while it isbeingused as asource of electrical energy ?

Answer»

`Pb RARR Pb^(2+)`
`Pb^(4+) rarr Pb`
`Pb^(2+) rarr Pb`
`Pb^(4+) rarr Pb^(2+)`

Solution :The reactioninvolved for leadaccumulator duringdischarging i.e, when cell is in theuse are
At anode : `Pb(s) + HSO_(4)^(-)(AQ) rarr PbSO_(4)(s) + H^(+) + 2E^(-)`
At cathode : `PbO_(2)(s)+ 3H^(+) +HSO_(4)^(-)(aq)`
`+2e^(-) rarr PbSO_4(s) + 2H_(2)O(l)`
OVERALL REACTION : `Pb(s) +PbO_(2)(s) + 2H^(+)`
`+2HSO_(4)^(-)(aq) rarr 2PbSO_(4)(s) + 2H_(2)O(l)`
Discussion
7727.

What changes occur in the nature of egg proteins on boiling ?

Answer»

Solution :On boiling , the globular proteins present in the egg undergo COAGULATION to FORM fibrous proteins .As a result , proteins lose their biological activity and THUS get denatured. Chemically , during denaturation, the secondary and tertiary structures of proteins are DESTROYED but primary structure remains INTACT.
Discussion
7728.

What is heterogeneous catalysis? Give example.

Answer»

Solution :HETEROGENEOUS catalysis is a PROCESS in which the reactants, products and CATALYST are PRESENTIN different phases.
e.g. `2SO_(2_(g)) + O_(2_(g)) overset(Pt(or)V_2O_5) to 2SO_(3_(g))`.
Discussion
7729.

What advantage do the fuel cells have over primary and secondary batteries?

Answer»

Solution :Primary batteries CONTAIN limited amounts of reactants. These CELLS become dead when the reactants are consumed. SECONDARY batteries can be recharged but take a long time for recharging. Fuel cells can be run CONTINUOUSLY so long as the reactants are supplied and the products are removed continuously.
Discussion
7730.

Which element does not show variable oxidation state ?

Answer»

Sc
V
Fe
Hg

Answer :a
Discussion
7731.

The two functional groups present in a typical carbohydrate are

Answer»

`-OH` and -COOH
`-CHO` and -COOH

`-OH` and `-CHO`

Solution :CARBOHYDRATES are OPTICALLY active polyhydroxy aldehyde or polyhydroxy KETONES.

and - OH functional groups are present in atypical carbohydrate.
Discussion
7732.

Write the structure of 3-methyl butanal.

Answer»

SOLUTION :`CH_(3)-underset(CH_(3))underset(|)(CH)-CH_(2)-CHO`
Discussion
7733.

The vapour pressure of two miscible liquids A and B are 300 and 500 mm of Hg respectively.In a flask 2 moles of A are mixed with 6 moles of B.Further to the mixture, 32 g of an ionic non-volatile solute MCl (partically ionised mol.mass =70 u) were also added.Thus, the final vapour pressure of solution was found to be 420 mm of Hg.Then, identify the correct statement(s): (Assume the liquid mixture of A and B to behave ideally ).

Answer»

The numerical value of RELATIVE lowering in vapour pressure upon ADDITION of solute MCl is `1//15`
The solute MCl is 25% ionised in the above question
The solute MCl is 23.33% ionised in the above question
Upon addition of excess `Pb(NO_3)_2`, the NUMBER of moles of `PbCl_2` precipitated is `2//35`

Solution :`P_0=X_AP_A^@+X_BP_B^@=2/8xx300+6/8xx500`=450 mm of Hg
Now, RLVP=`(P_0-P_S)/P_0=(450-420)/450=1/15`
Also, RLVP =`(("in")/("in"+N))`
`1/15=((32i)/70)/((32i)/70+8) :. i=1.25=(1+(2-1)alpha)`. So `alpha=0.25` (or 25 %)
`:. n_(Cl^(-))` produced `=25/100xx32/70=4/35`
`:. n_(PbCl_2)` precipitated =`1/2xx4/35=2/35`
Discussion
7734.

What is the monomer of natural rubber ?

Answer»

SOLUTION :ISOPRENE
Discussion
7735.

Write the following: (i) IUPAC name for the monomer of natural rubber. (ii) The partial structure of polythene.

Answer»

SOLUTION :(i) IUPAC NAME for the monomer of natural rubber is 2-methyl-1,3-butadiene
(II) The partial STRUCTURE of polythene is `(-CH_(2)-CH_(2)-)`
Discussion
7736.

Which constitutes the enamel of our teeth ?

Answer»

`Ca_3(PO_4)_2`
`CaF_2`
`MgCl_2`
`CaBr_2`

ANSWER :A
Discussion
7737.

Which of the following are inner orbital complex (i.e., involving d^(2)sp^(3) hybridisation) and is paramangetic in nature?

Answer»

`[Mn(CN)_(6)]^(3-),[Fe(CN)_(6)]^(3-),[Co(C_(2)O_(4))_(3)]^(3-)`
`[MnCl_(6)]^(3-),[FeF_(6)]^(3-),[CoF_(6)]^(3-)`
`[Mn(CN)_(6)]^(3-),[Fe(CN)_(6)]^(3-)`
`[MnCl_(6)]^(3-),[Fe(CN)_(6)]^(3-),[Co(C_(2)O_(4))_(3)]^(3-)`

Solution :`[Mn(CN)_(6)]^(3-) and [Fe(CN)_(6)]^(3-)` are inner ORBITAL complexes and paramagnetic while `[Co(C_(2)O_(4))_(3)]^(3-)` is diamagnetic in nature.
Discussion
7738.

Why is reduction of a metal oxide easier if the metal formed is in liquid state at the temperature adopted for reduction?

Answer»


ANSWER :Refer to the answer of Qn. 3 (II) NCERT Intext Questions.
Discussion
7739.

The treatment of CH_(3)MgX " with " CH_(3)C-C-H produces

Answer»

`CH_(3)-CH=CH_(2)`
`CH_(3)C=C-CH_(3)`
`CH_(2)-HC=CH-CH_(3)`
`CH_(4)`

Solution :Writing the REACTION we get
`CH_(3)MgX+CH_(3)-C-=C-H to CH_(3)-C-=CMgX+CH_(4)(g)`
Discussion
7740.

When ammonia is heated with cupricoxide . How many electrons will each ammonia molecule loose.

Answer»


SOLUTION : each `NH_3` LOSES `3E^(-)s`
Discussion
7741.

Which of the following is an aldohexose

Answer»

Cellulose
Sucrose
galactose
Raffinose

Answer :C
Discussion
7742.

When benzene diazonium chloride undergoes hydrolysis, it gives

Answer»

Chlorobenzene
Benzyl alcohol
Phenol
Benzene

Answer :C
Discussion
7743.

Which is not correct for transition metals?

Answer»

VARIABLE OXIDATION states
Complex formation
Partially FILLED d-orbitals
All the IONS are colourless

Answer :D
Discussion
7744.

Which of the following compounds has colour but no unpaired electrons?

Answer»

`KMnO_(4)`
`K_(2)MnO_(4)`
`MnSO_(4)`
`MnCl_(2)`

Solution :Electronic configuration of `Mn` is `[AR]3d^(5)4s^(2)`. Being TRANSITION metal it bas 7 valence electrons and all are involved in bond formation in `MnO_(4)^(-)`. Hence it has no unpaired electron.
Discussion
7745.

What is the pH of a 0.50 M aqueous NaCN solution? pk of CN^- is 4.70.

Answer»


ANSWER :11.5
Discussion
7746.

Weight of non-volatile solute urea neede to be dissolved in 90 gm of water in order to decrease the vapour pressure by 25% . Theanswer after dividing with 20 is

Answer»
Discussion
7747.

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
7748.

When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N the solution turns light blue.Addition of aqueous NaCl to the blue solution gives a white precipitate O.Addition of aqueous NH_(3) dissolves O and gives an intense blue solution. The compound N is :

Answer»

`AgNO_(3)`
`Zn(NO_(3))_(2)`
`Al(NO_(3))_(3)`
`Pb(NO_(3))_(2)`

Solution :`Cu(M)+AgNO_(3)(N)`(queous colourless solution) `to` RESULTANT solution CONTAINS `Cu(NO_(3))_(2)` (blue solution) and `AgNO_(3)` (colourless solution)
Note: Here it is considered that complete `AgNO_(3)` is not utilized in the reaction.
`AgNO_(3)(AQ)+NaCl(aq) to AgCl darr`(white) `(O)+NaNO_(3)`
Solution containing white ppt. of `AgCl` also contains `Cu(NO_(3))_(2)` which developed DEEP blue colouration with aqueous `NH_(3)` solution
`AgCl darr ("white")+2NH_(3)(aq.) to [Ag(NH_(3))_(2)]^(+)`
`Cu(NO_(3))_(2)(aq.)+4NH_(3) (aq.) to [Cu(NH_(3))_(4)](NO_(3))_(2)` (deep blue solution)
So, METAL rod `M` is `Cu`.
The compound `N` is `AgNO_(3)` and the final solution contains `[Ag(NH_(3))_(2)]^(+)` and `[Cu(NH_(3))_(4)]^(2+)`
Discussion
7749.

Which compound has the highest boiling point?

Answer»

Acetone
Diethyl ether
Methanol
Ethanol

Answer :D
Discussion
7750.

When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N the solution turns light blue.Addition of aqueous NaCl to the blue solution gives a white precipitate O.Addition of aqueous NH_(3) dissolves O and gives an intense blue solution. The final solution contains

Answer»

`[Pb(NH_(3))_(4)]^(2+)` and `[CoCl_(4)]^(2-)`
`[Al(NH_(3))_(4)]^(3+)` and `[Cu(NH_(3))_(4)]^(2+)`
`[Al(NH_(3))_(2)]^(+)` and `[Cu(NH_(3))_(4)]^(2+)`
`[Al(NH_(3))_(2)]^(+)` and `[Ni(NH_(3))_(6)]^(2+)`

Solution :`Cu(M)+AgNO_(3)(N)`(queous colourless solution) `to` Resultant solution contains `Cu(NO_(3))_(2)` (blue solution) and `AgNO_(3)` (colourless solution)
Note: Here it is considered that complete `AgNO_(3)` is not UTILIZED in the reaction.
`AgNO_(3)(aq)+NaCl(aq) to AgCl darr`(white) `(O)+NaNO_(3)`
Solution containing white ppt. of `AgCl` also contains `Cu(NO_(3))_(2)` which developed deep blue colouration with aqueous `NH_(3)` solution
`AgCl darr ("white")+2NH_(3)(aq.) to [Ag(NH_(3))_(2)]^(+)`
`Cu(NO_(3))_(2)(aq.)+4NH_(3) (aq.) to [Cu(NH_(3))_(4)](NO_(3))_(2)` (deep blue solution)
So, Metal rod `M` is `Cu`.
The compound `N` is `AgNO_(3)` and the final solution contains `[Ag(NH_(3))_(2)]^(+)` and `[Cu(NH_(3))_(4)]^(2+)`
Discussion