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3201.

What happens when ? (i)

Answer»


ANSWER :`(##ALN_CHM_C09(II)_E01_781_A01##)`
Discussion
3202.

What is a primary cell ? Describe the construction and working of dry cell,

Answer»

Solution :Primary CELLS are those in which the electrode reactions cannot be reversed by an external electric energy source. In these cells, the reaction occurs only once and after use they BECOME dead. Therefore, they are not chargeable.
(a) Dry cell. The dry cell was invented by G. Leclanche. It consists of a zinc cylinder. This is filled with a paste of `NH_(4)Cl` and little of `ZnCl_(2)` in the form of paste in water. The zinc cylinder ACTS as anode. The cathode is a carbon rod. The carbon rod is surrounded by a black paste of manganese dioxide `(MnO_(2))` and carbon powder.
When the cell is operating, zinc loses electrons and `Zn2^(+)` ions dissolve in the electrolyte. The electrons pass. around the external circuit and are taken up at cathode. This causes DISCHARGE of `NH_(4)^(+)` ions from the electrolyte.
The reactions occurring at the electrodes are given below :
At anode
`ZntoZn^(2+)+2e^(-)`
At cathode

`2NH_(4)^(+)(aq)+2MnO_(2)(s)+2e^(-)toMn_(2)O_(3)(s)+NH_(3)+H_(2)O`
It gives a voltage of about 1.5 V.
(ii) Uses. The dry cells are used in torches, toys, flash lighters, calculators, tape-recorders and in many other devices.
Discussion
3203.

Which of the following reaction do not yield cyclohexanone as major product?

Answer»




ANSWER :D
Discussion
3204.

Which of the following ether cannot be prepared by Williamson's synthesis

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All

Answer :C
Discussion
3205.

Which compound is most reactive towards SN^2reaction

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`CH_3CH_2CH_2Cl`
`CH_2=CH -CH_2Cl`
`CH-=C - CH_2Cl`

ANSWER :C
Discussion
3206.

Which of the following on thermal decompositrion gives oxygen gas ?

Answer»

`Ag_(2)O`
`Pb_(3)O_(4)`
`PbO_(2)`
All of these

Solution :`2Ag_(2)O (s) to 4Ag(s)+O_(2)(g)`
`2Pb_(2)O_(4)(s) to 6PbO(s)+O_(2)(g)`
`2PbO_(2)(s) to 2PbO(s)+O_(2)(g)`
Discussion
3207.

Which In K vs 1/T plot is correct for an equilibrium that shits toward reactants at higher temperatures?

Answer»




ANSWER :C
Discussion
3208.

Which of the following are examples of redox electrodes ?

Answer»

`Pt|Sn_((aq))^(2+), Sn_((aq))^(4+)`
`PtCl_(2(g))|Cl_((aq))^(-)`
`Ag|AgCl_((s)), KCl_((aq))`
`Cu_((s))|CuSO_(4(aq))`

SOLUTION :`SN^(2+) hArr Sn^(4+)+2e^(-)`
Discussion
3209.

Which of the following statements about amino acids is false

Answer»

They are constituents of all proteins
Alanine having one amino and one carboxylic group.
Most naturally occuring amino ACIDS have D-configuration.
Glycine is the only naturally occuring amino acid which is OPTICALLY inactive.

Solution :Most naturally occuring amino acids have L-configuration.
Discussion
3210.

When value of equilibrium constant is more than 1, then for spontaneous reaction . . .

Answer»

Concentration of reactant and PRODUCT is same. (a) `gt1`.
Less product is OBTAINED. (b) 0
More product is obtained. (C) `lt1`
No product is POSSIBLE. (d)`lt0`

SOLUTION :More product is obtained. (c) `lt1`
Discussion
3211.

Which of the following solution, where physical state of solute and solvent is liquid and solid, respectively ?

Answer»

Air CONTAINING moisture
Zinc dissolved in MERCURY
Solution of naphthalene in BENZENE
Sugar solution

Answer :B
Discussion
3212.

What is crystal field stabilization energy (CFSE) ?

Answer»

<P>

Solution :The crystal field stabilisation energy is DEFINED as the energy difference of electronic configuration in the ligand field `(E_(LF))` and the isotropic field (Eiso).
`CFSE(DeltaE_(0))={E_(LF)}-{E_(iso)}`
`={[n_(t_(2g))(-0.4)+n_(e_(g))(0.6)Delta_(0)+n_(p)P}-{n._(p)P}`
Here `n_(t_(g))` is the number of electrons in `t_(2g)` orbitals
`n_(e_(g))` is the number of electrons in `e_(g)` orbitals
`n_(p)` is the number of electrons in the ligand field
`n._(p)` is the number of electrons in the isotropic field
Discussion
3213.

Which is not a condensation polymer ?

Answer»

Nylon-66
Glyptal
Dacron
PTFE (POLYTETRAFLUOROETHENE)

ANSWER :D
Discussion
3214.

Which of the following is a 1^(@) amine and acts as a neurotransmitter in the brain ?

Answer»

DOPAMINE
Andrenaline
Caffeine
Nicotine.

Solution :Dopamine is a `1^(@)` AMINE and ACTS as a neutrotransmitter in the BRAIN.
Discussion
3215.

x=moles of HCHO consumed. Value of (x) will be.

Answer»

Solution :
ONE MOLE of HCHO gives `1-CH_(2)-OH` group. TOTAL `-CH_(2)-OH` group added in product=6
Hence moles of HCHO consumed=6.
Discussion
3216.

Which of the following is not a mixture ?

Answer»

GASOLINE
LIQUID petroleum gas
distilled water
iodized table salt

Solution :Distilled water is a compound
Discussion
3217.

Which is used to identify glucose :

Answer»

NEUTRAL FERRIC chloride
`CHCI_3+KOH`(alc.)
AMMONIACAL `AgNO_3`
`C_2H_5ONa`

Answer :C
Discussion
3218.

Which of the following alloys contains one metal same as brass ?

Answer»

ALNICO
MAGNALIUM
DURALIUM
Invar

Answer :C
Discussion
3219.

What are inner transition elements?

Answer»

Solution :The inner transition elements have two SERIES of elements. (i) Lanthanoids (ii) Actinoids
2. Lanthanoid series consists of 14 elements from Cerium`""_(58)Ce`to Lutetium`""_(71)Lu` following LANTHANUM`""_(57)La`. These elements are characterised by the PREFERENTIAL filling of 4f orbitals.
3. Actinoids consists of 14 elements from Thorium`""_(90)Th`to Lawrencium`""_(103)Lr`following Actinium`""_(89)Ac`. These elements are characterised by the preferential filling of 5F orbital.`
Discussion
3220.

Which one is more soluble in diethyl ether, anhydrous AlCl_(3) or hydrated AlCl_(3) ? Explain in terms of bonding.

Answer»

Solution :(i) Anhudrous `AlCl_(3)` is an electro-deficient compound while hydrated `AlCl_(3)` is not.
(ii) Therefore, anhydrous `AlCl_(3)` is more soluble in diethyl EITHER because the oxygen atom of ether donates a pair of electrons to the vacant p-orbital on the Al atom in AlCl3 forming a co-ordinate bond.
(iii) In case of hydrated `AlCl_(3)`, Al is not electron deficient, SINCE, `H_(2)O` has already donated a pair of `E^(-)` to it.
Discussion
3221.

Which of the following is polysaccharide?

Answer»

Glucose
Ribose
Sucrose
starch

Answer :D
Discussion
3222.

Which of the following solids has highest conductivity of heat and electricity ?

Answer»

W 
SIC 
KCI 
ICE 

ANSWER :A
Discussion
3223.

Whichof the followingstatementconcerningconcerningprobabilitydensity (Psi^(2)) andradialdistributionfunction (4 pir^(2) Psi) for a s - orbit of H - likespecies is correct ?

Answer»

`Psi^(2)` isminimum at nucleusbut `4 PI r^(2) Psi^(2)`is maximum atnucleus .
`Psi^(2)`is maximum at nucleus but `4 pi r^(2) Psi^(2)` is minimumat nucleus .
Both `Psi^(2)`and `4pir^(2) Psi^(2)`are maximumat nucleus .
Both `Psi^(2)`and `4PI r^(2) Psi^(2)`

Solution :`Psi =(1)/(sqrt(pi)) ((1)/(a_(0)))^(3//2) = e^((-(r)/(a_(0))))`
HENCE , `Psi^(2)` is maximum atr = 0 , but `4 pi r^(2) Psi^(2)`is MINIMUM at r = 0
Discussion
3224.

Which of the following reaction are correct?

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ANSWER :A::B::C::D
Discussion
3225.

Which colourless gas turns brown in air ?

Answer»

NO
`NO_(2)`
`N_(2)O_(4)`
`N_(2)O_(5)`

ANSWER :A
Discussion
3226.

Which one of the following reactions occurs at the anode on electrolysis of aq., solution of CuCl_(2) ?

Answer»

`Cu to Cu^(2+) + 2 e^(-)`
`2 Cl^(-) to Cl_(2) + 2E^(-)`
`2 H_(2)O to O_(2) + 4 H^(+) + 4 e^(-)`
`4 Cl^(-) + 2 H_(2)O to 4 HCL + O_(2) + 4 e^(-)`

SOLUTION :`Cl^(-)` ions are oxidizedmore easily than `H_(2)O`.
Discussion
3227.

The standard reduction potentials for two reactions are given below:AgCl(s) + e^(-) to Ag(s) + Cl^(-) , E^@ = 0.22 VAg^(+)(aq) e^(-)+e^(-) toAg(s), E^@ = 0.80V The solubility product of AgCl under standard conditions of temperature (298 K) is given by

Answer»

`1.5 XX 10^(-10)`
`1.5 xx 10^(-8)`
`3.2 xx 10^(-10)`
`3.2 xx 10^(-8)`

ANSWER :A
Discussion
3228.

Which of the following shows nitrogen with its increasing order of oxidation number ?

Answer»

`NO LT N_(2)O lt NO_(2) lt NO_(3)^(-) lt NH_(4)^(+)`
`NH_(4)^(+) lt N_(2)O lt NO_(2) lt NO_(3)^(-) lt NO`
`NH_(4)^(+) lt N_(2)O lt NO lt NO_(2) lt NO_(3)^(-)`
`NH_(4)^(+) lt NO lt N_(2)O lt NO_(2) lt NO_(3)^(-)`

Solution :`{:("Compound","O.S. of N"),(N_(2)O," "+1),(NO," "+2),(NO_(2)," "+4),(NO_(3)^(-)," "+5),(NH_(4)^(+)," "-3):}`
Therefore increasing ORDER of oxidation state of N is :
`NH_(4)^(+) lt N_(2)O lt NO lt NO_(2) lt NO_(3)^(-)`
Discussion
3229.

The smelting of iron in a blast furnace involves the following processes:

Answer»

COMBUSTION
reduction
Slag formation
fusion

Answer :A,B,C,D
Discussion
3230.

Write simple chemical tests and observations used to distinguish between the following compounds. (ii) Phenol and benzoic acid

Answer»


ANSWER :Benzoic PRODUCES effervescence with the LIBERATION `CO_2` when treated with sodium BICARBONATE solution PHENOL does not.
Discussion
3231.

What happens when?(a) Excess caustic soda is added to a solution of aluminium chloride. (b) Aluminium is heated with caustic soda solution: (c) A mixture of borax and cobalt oxide is heated in flame. (d) (i) BF_(3) reacts with water.(ii) Al_(4)C_(3) reacts with water.

Answer»

Solution : (a) `AICI_(3) + 3NaOHtoAl(OH)_(3) +3NaCI`
`Al(OH)_(3) +NaOHtoNaAlO_(2)+ 2H_(2)O`
(b)` 2AI+2NaOH+2H_(2)Oto2NAIO_(2) +3H_(2)`
(c) `Na_(2)B_(4)O_(7)10_(2)Ooverset(Delta)underset(-10H_(2)O)toNa_(2)B_(4)O_(7)to2NaBO_(2)+B_(2)O_(3)B_(2)O_(3)+CoOtounderset(Cobaitmiabcrbcate)(CO(BO_(2))_(2))`
(d)(i)`4BF_(3)+6H_(2)OtoH_(3)BO_(3)+3H_(3)O+3BF_(4)^(-)`
(II)`AI_(4)C_(3)+12H_(2)Oto4AI(OH)_(3)+3CH_(4)`
Discussion
3232.

Which of the following reagents can be used to test carboxylic group?

Answer»

`NaHCO_(3)`
`FeCl_(3)`
Alcohol in presence of CONC. `H_(2)SO_(4)`
Ceric AMMONIUM NITRATE

ANSWER :A::B::C
Discussion
3233.

Which isotope on bombardment with alpha-particles will give ._(8)O^(17) and ._(1)H^(1)

Answer»

`._(8)O^(16)`
`._(7)N^(14)`
`._(7)N^(15)`
`._(6)C^(14)`

Solution :`._(7)N^(14) + ._(2)He^(4) rarr ._(8)O^(17) + ._(1)H^(1)`
Discussion
3234.

When tetraamminechloridonitrito cobalt (III) nitrate is dissolved in water, how many ions will be formed from one molecule -

Answer»

4
3
2
0

Answer :C
Discussion
3235.

The vapour pressure of aqueous solution of methanol is

Answer»

EQUAL to WATER
Equal to METHANOL
More than water
LESS than water

Answer :C
Discussion
3236.

Which one of the following halogens forms only one acid?

Answer»

`Br_(2)`
`Cl_(2)`
`F_(2)`
`I_(2)`

SOLUTION :`F_2` forms only one oxo acid, HOF (or HFO), which is prepared by PASSING `F_2` over ice at - `40^(@)C`.
`F_(2)+H_(2)O overset(-40^(@)C) to HOF+HF`
In `OF^(-)` ion, Fatom has no d-orbitals in its valence shell, and THUS it connot form pa-dn bonds with O-atom. Consequently, OF is not STABILIZED and therefore, HOF is highly unstable.
Other halogens form a series of oxo acids such as `HXO, HXO_2, HXO_3 and HXO4`. Anions of these oxo acids are stabilized by pr-da bonding between full 2p-orbitals on oxygen atoms with empty-orbitals on halogen atoms, except fluorine.
Discussion
3237.

Which of the following common names and IUPAC names is/are correctly matched?

Answer»

t-Butyl ALCOHOL and 2-methyl-2-propanol
s-Butyl alcohol and 1-methyl-1-propanol
iso-Butyl alcohol and 2-methyl-1-propanol
neo-Pentyl alcohol and 2,2-dimethyl-1-propanol

Answer :A,C
Discussion
3238.

Which of the following reaction does not produce phosphine?

Answer»

<P>`Ca_(3)P_(2)+H_(2)Orarr`
`AlP+HC lrarr`
`PH_(4)I+NaOHrarr`
`H_(3)PO_(4)OVERSET("HEAT")rarr`

Answer :D
Discussion
3239.

Which equimolal concentrated solution has highest freezing point ?

Answer»

GLUCOSE
`LA(NO_(3))_(3)`
`Ca(NO_(3))_(2)`
VINEGAR

ANSWER :A
Discussion
3240.

The total ionic strength (total molarity of all the ions) containing 0.2 M CuSO_(4) and 0.1M Al_(2)(SO_(4))_(3) is

Answer»

0.5 M
0.7 M
0.9 M
1.2 M

SOLUTION :In 1 L solution, moles of `Cu^(2+)=0.2,` moles
`SO_(4)^(2-)=0.2,` moles of `Al^(3+)=2xx0.1=0.2,` moles
of `SO_(4)^(2-)=3xx0.1=0.3`
Total moles of all ions = `0.2+0.2+0.2+0.3=0.9`
Hence, molarity of all the ions = 0.9 M.
Discussion
3241.

Which of the following configuration will not give John- teller distortion ( In both HS & LS complexes ) ?

Answer»

`d^(8)`
`d^(7)`
`d^(6)`
`d^(4)`

Solution :`d^(8)` has symmetric DISTRIBUTION of ELECTRONS, there fore no JAHN Teller EFFECT
Discussion
3242.

Which concept best explains the fact that o-nitrophenol is more volatile than p-nitrophenol ?

Answer»

RESONANCE
Steric hindrance
Hydrogen bonding
HYPER CONJUGATION

Answer :C
Discussion
3243.

Which of the following reaction will give racemic mixture ?

Answer»




ANSWER :A
Discussion
3244.

X overset(CHCl_(3), KOH)rarr Y overset(H_(3)O^(+))rarr X. If 'Y' is a compound with awful odour, identify the starting compound X ?

Answer»

SOLUTION :`1^(@)` AMINE
Discussion
3245.

Which of the following vitamins is //are water soluble?

Answer»

VITAMIN A
Vitamin C
Vitamin K
Vitamin B

Answer :B::D
Discussion
3246.

What happens when NH_4NO_3 is heated (equation only) ?

Answer»

SOLUTION :`NH_4NO_3 oversetDeltararr N_2O UARR + H_2O`
Discussion
3247.

What is the name of the reaction of phenol with chloroform and aqueous alkali?

Answer»

KOLBE's REACTION
CUMENE SYNTHESIS
Riemer-Tiemann reaction
Schottan Baumann reaction

SOLUTION :Riemer-Tiemann reaction
Discussion
3248.

Which gaseous element exhibits allotropy?

Answer»

SOLUTION :OXYGEN
Discussion
3249.

Which of the following compounds do not produce pink colour with Schiff's reagent?

Answer»

Formaldehyde
Propan-2-one
Pentan-3-one
Both (B) and (C)

ANSWER :A::B::C::D
Discussion
3250.

What is the emf developed by a single lead storage battery?

Answer»

SOLUTION :The EMF of a SINGLE CELL is about 2V.
Discussion