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20401.

When phenol is reacted with CHCl_(3) and NaOH followed by acidification, salicyldehyde is obtained . Which of the following species are involved in the above mentioned reactioin as intermediates

Answer»




Solution :
This REACTION is REIMER - Tiemann reaction and the MEACHANISM is REPRESENTED as follows : MECHANISM : Step I :
Discussion
20402.

Which ofthe following pair of ions have the same colour ?

Answer»

`""_(58)CE^(3+), ""_(63)Eu^(3+)`
`""_(59)Pr^(3+), ""_(64)GD^(3+)`
`""_(62)Sm^(3+), ""_(66)Dy^(3+)`
`""_(71)Lu^(3+), ""_(69)Tm^(3+)`

Solution :Only `Sm^(3+) and Dy^(3+)` have 5 and 9 (14-5) electrons. The IONS having `4f^(n) and 4f^(14-n)`electrons have same colour.
Discussion
20403.

Which one of following is a disproportionation reaction?

Answer»

`XeO_3 + NaOH +H_2O to`
`XeO_3 + Pu^(2+) + H^(o+)to`
`XeF_4 + NO_2 to`
`XeF_4 + H_2O underset("hydrolysis")overset("complete")to`

Solution :a) `XeO_3 + OH^(Theta)hArr HXeO_4^(-) , overset(+6)(2HXeO_4^(-)) + 2OH^(Theta) to overset( + 8" "4-)(XeO_6^(-)) + XE^(O) + 2H_2O+ O_2`
d) `overset( +4) (6XeF_4) + 12 H_2Oto overset(+6)(2XeO_3) + 24HF + 4overset(0)Xe + 3O_2`
Discussion
20404.

What happens when potassium iodide is added to CuSO_4 solution ?

Answer»

SOLUTION :`2CuSO_4 + 4KI = 2CuI_2 + 2K_2SO_4`
Discussion
20405.

Which of the following combination is INCORRECT?

Answer»

<P>(I) (III) (Q)
(II) (IV) ( R )
(II) (i) (P)
(IV) (ii) (Q)

Answer :D
Discussion
20406.

Write name and structure of monomers of following polymer : Teflon

Answer»

SOLUTION :TETRAFLUOROETHENE
`F_2C = CF_2`
Discussion
20407.

What is the quantity of hydrogengas liberatedwhen 46 gsodium reacts withexcessethanol ? (Given atomic mass of Na = 23)

Answer»

`2.4 XX 10^(-3) kg `
`2.0 xx 10^(-3) kg `
`4.0 xx 10^(-3) kg `
`2.4 xx 10^(-2) kg `

Answer :B
Discussion
20408.

The solubility of an aqueous solution of Mg(OH)_2 be x then its K_(sp) is……..

Answer»

`4x^3`
`108x^5`
`27x^4`
9x

Solution :`MG(OH)_2leftrightarrowMg^(2+)+2OH^-`
`x (2X)^2`
`K_(sp)=4x^3`
Discussion
20409.

What is the role of depressant (NaCN) in Froth-Flotation method?

Answer»

SOLUTION :It separates TWO sulphate ores/ALLOWS PbS to COME with the forth/selectively prevents ZnS from COMING to the forth but allows PbS to come with the forth.
Discussion
20410.

When two half cells of Daniel cell is connected, a spontaneous __________ reaction takes place resulting in the flow of electrons from anode to cathode

Answer»

reduction
oxidation
redox
hydration

Answer :C
Discussion
20411.

Which one of the following is most reactive in nucleophilic substitution ?

Answer»




ANSWER :D
Discussion
20412.

The vapour pressures of benzene and toluene at 293 K are 75 mm and 22 mm Hg respectively. 23.4 g of benzene and 64.4 g of toluene are mixed. If the two form an ideal solution, calculate the mole fraction of benzene in the vapour phase assuming that the vapours are in equilibrium with the liquid mixture at this temperature.

Answer»

<P>

Solution :In the LIQUID PHASE, `n_(B)=23.4//78=0.3, n_(T)=64.4//92=0.7." Hence, "x_(B)=0.3, x_(T)=0.7`
`p_(B)=0.3xx75=22.5 mm, p_(T)=0.7xx22=15.4 mm , "Tota vapour PRESSURE "=22.5+15.4=37.9 mm"`
Mole FRACTION of benzene in the vapour phase `=22.5//37.9=0.59.`
Discussion
20413.

Thermosetting polymer is

Answer»

Nylon-6
Nylon-6,6
Bakelite
SBR

Answer :A::B::C
Discussion
20414.

Which type of hybridisation explains the trigonal bipyramidal shape of SF_4?

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SOLUTION :`sp^3d.`
Discussion
20415.

Which of the following species can function both as oxidizing as well as reducing agent ?

Answer»

`CL^(-)`
`ClO_(4)^(-)`
`ClO^(-)`
`MnO_(4)^(-)`

Answer :C
Discussion
20416.

When the value of entropy is greater, then the ability for work is:

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Maximum
Minimum
Medium
None of these

Answer :A
Discussion
20417.

Which elements gives maximum balanced oxide

Answer»

V
Cr
MN
Fe

Solution :Among the transition metals Mn FORMS maximum no. of OXIDES.
`underset("BASIC")(MnO)" "underset("amphoteric")(Mn_(3)O_(4))" "underset("amphoteric")(Mn_(2)O_(3))" "underset("amphoteric")(MnO_(2))" "underset("ACIDIC")(Mn_(2)O_(7))`
Discussion
20418.

Which of the following statement is /are correct ?

Answer»

Out of trimethylamine and trimethylphsophine , trimethylamine has higher DIPOLE moment
Out of `(SiH_3)_2O` and `(CH_3)_2O, (SIH_3)_2O` is more basic
C-C bond length (in pm) in `C_2` molecule is greater than O-O bond length in `O_2` molecule
`N(SiMe_3)_3` and `BF_3` molecules are isostructural

Solution :Nitrogen is more electronegative than phosphorus.

So, dipole moment of trimethylamine is greater than trimethyl phosphaine.

In trisilyl ether the lone pair of electron on oxygen atom is LESS easily available for donation because of `ppi-dpi` DELOCALISATION DUE to presence of the vacant d-orbital with Si.This however is not possible with carbon in `CH_3-C-CH_3` due to the absence of d-orbital making it more basic.
(C )Bond order of `C_2` and `O_2` are same i.e. 2. In `C_2` molecules both bonds are `pi`-bonds whereas, there is one `sigma` and one `pi` bonds in `O_2` molecule.
`C_2`=131 pm , `O_2`=121 pm .
(D)
Discussion
20419.

Which mixture is used for prevention of impregnation ?

Answer»

Estrogenic and progestogenic COMPOUNDS.
Astrogenic and Testogenic compound.
Norethindrone and progestogenic compounds.
All can be USED 

SOLUTION :Estrogenic and progestogenic compounds.
Discussion
20420.

The total number of isomers including stereoisomers that could be obtained by replacing two hydrogen atoms of propane by two chlorine atoms are.

Answer»


Solution :Five, i.e., `CH_(3)CH_(2)CH_(2)Cl_(2),(+) and (-)`
`CH_(3)overset(**)(C)HClCH_(2)Cl,CH_(3)C Cl_(2)CH_(3),ClCH_(2)CH_(2)CH_(2)Cl`
Discussion
20421.

Whichis thecorrectgraPsicalrepresentationbasedon photoelectriceffect ?

Answer»

I &II
II&III
III& IV
II&IV

Answer :D
Discussion
20422.

Write the names of the enzymes whose deficiency causes albinism and phenylketone urea.

Answer»

SOLUTION : Tyrosinase deficiency CAUSES albinism and the deficiency of PHENYLALANINE hydroxylase causes phenylketone UREA.
Discussion
20423.

Which of the following factors favours S_(N)2 mechanism?

Answer»

Polar SOLVENT
Low conc. Of NUCLEOPHILE
STRONG nucleophile
`3^(@)` alkyl halide

Answer :C
Discussion
20424.

What amount of work is needed to move an electron against a potential difference of 1.0 volt? What amount of work is needed for 1 mole of electrons and what does this value represent?

Answer»

SOLUTION :`1.602 XX 10^(-10) J, 96470 J "mole"^(-1)` , Faraday constant
Discussion
20425.

What are antimicrobials? Mention its function and its uses.

Answer»

Solution :(i) ANTIMICROBIALS inhibits bacterial cell WALL BIOSYNTHESIS.
(ii) e.g., penicillin, ampicillin.
(iii) It is used to TREAT skin infections, dental infections, ear infections, respiratory tract infections. PNEUMONIA, urinary tract infections and gonorrhoea.
Discussion
20426.

The relation between energy of a radiation and its frequency was given by:

Answer»

DE Broglie
Elinsten
Planck
Bohr

ANSWER :C
Discussion
20427.

Which condensation method is used to prepare sulphur sol?

Answer»

Hydrolysis
DECOMPOSITION
Reduction
Peptisation

Solution :Decomposition
Discussion
20428.

What is nucleoside?

Answer»

Solution :Statement
Detailed Answer :
A PENTOSE sugar with a NITROGEN BASE and a phophate group is CALLED a NUCLEOSIDE.
Discussion
20429.

When 1 mole of ice melt at 0^(@)C and at constant pressure of 1 atm. 1440 calories of heat are absorbed by the system. The molar volumes of ice and water are 0.0196 and 0.0180 litre respectively. Calculate DeltaHandDeltaE for the reaction.

Answer»

SOLUTION :`DeltaH~=DeltaE=1440"CALORIES"`
Discussion
20430.

Which one of the following substances does not have a melting point ?

Answer»

Bromine
Sodium chloride
Mercury
Glass

Solution :Mercury EXISTS in liquid state HENCE, it has no MELTING POINT.
Discussion
20431.

Which one of the following statements is incorrect regarding vitamins ?

Answer»

Vitamin A is ESSENTIAL for growth and VISION 
Vitamin D is essential for development of bones 
A red coloured carotene in the body breaks into vitamin C 
Vitamin K is essential for blood coagulation 

ANSWER :C
Discussion
20432.

The uncertainty in the momentum of an electron is 1.0xx10^(-5)kgms^(-1). The uncertainty in position will be (h=6.6xx10^(-34)kgm^(2)s^(-1))

Answer»

`5.25xx10^(-28)m`
`1.05xx10^(-26)m`
`5.25xx10^(-30)m`
`1.05xx10^(-28)m`

Solution :`DELTAX xx Deltap=h/(4pi)`
`DELTA x=h/(4pixx Deltap)=(6.6xx10^(-34))/(4xx2/7xx1xx10^(-5))`
`=5.25xx10^(-30)m`
Discussion
20433.

Which of the following is water soluble vitamin ?

Answer»

VITAMIN 'E'
Vitamin 'K'
Vitamin 'B'
Vitamin 'A'

Answer :B
Discussion
20434.

Two different first order reaction have rate constants k_1 and k_2 at T_1(k_1 gt k_2) > If temperature is increased from T_1 " to " T_2. Then new constants become k_3 and k_4 respectively. Which among the following relations is correct /

Answer»

`k_1 GT k_2 = k_3 = k_4`
`k_1 LT k_3 and k_2 lt k_4`
`k_1 = k_3 = k_4`
`k_1 gt k_2 gt k_3 gt k_4`

ANSWER :B
Discussion
20435.

The standard hydrogen electrode is written in

Answer»

`PT,H_(2)|H^(+)(1 M)`
`Pt,H_(2) H^(+)(a//M)`
`Pt, H_(2)(1 ATM)|H^(+)(1M)`
`Pt//H_(2),H^(+)`

SOLUTION :CONVENTION to represent the cell.
Discussion
20436.

Which has the maximum number of molecules among the following ?

Answer»

44 g of `CO_(2)`
48 g `O_(2)`
8 g `H_(2)`
64 g `SO_(2)`

Solution :`44g" of "CO_(2)=(44)/(44)"mole"="1 mole,"`
`"48 g of "O_(2)=(48)/(32)" mole"="1.5 mole"`
`8G H_(2)=(8)/(2)" mole = 4 mole,"`
`"64 g SO"_(2)=(64)/(64)" mole = 1 mole"`
1 mole of any gas contains AVOGADRO's no. of molecules
Discussion
20437.

What is colloidal sulphur ? How can it be obtained ?

Answer»
Discussion
20438.

The standard reduction potentials at 25^@ of Li^+ [Li,Ba^(2+)[Ba,Na^+]Na and Mg^(2+)]Mg are-3.05,-2.76,-2.71 and -2.37V respectively . Which is strogest reducing agent.

Answer»

Li
Ba
Na
Mg

Answer :A
Discussion
20439.

Which electronic configuration represents the configuration of the most electropositive element ?

Answer»

`[He]2s^1`
`[XE]6S^1`
`[He]2S^2`
`[Xe]6S^2`

ANSWER :B
Discussion
20440.

Which of the following process is based on the formation of complex compounds ?

Answer»

BELGIAN process
Mac ARTHUR FOREST process
Poling process
Mond process

Answer :B::D
Discussion
20441.

Which of the following is not true for S_(N) 1 reaction ?

Answer»

Favoured by polar solvents
`3^(@)` - alkyl HALIDES GENERALLY react through `S_(N) 1` reaction
The rate of the reaction does not depend upon the molar concentration of the nucelophile .
`1^(@)`- alkyl halides generally react through `S_(N)`1 reaction .

Solution :`S_N 1` reaction is favoured by bulky groups on the carbon atom attached to HALOGENS , i.e., theorder of REACTIVITY is `underset("Tertiary") (R_(3)C) - X gt underset("Secondary") (R_(2) CH)- X gt underset("Primary") (RCH_(2)) - X gt underset("Methyl") (CH_(3) - X)`
Discussion
20442.

Which of the following ionsis paramagnetic?

Answer»

`[Ni(H_(2)O)_(6)]^(2+)`
`[Fe(CN)_(6)]^(4-)`
`[Ni(CO)_(4)]`
`[Ni(CN)_(4)]^(2-)`

Solution :In `[Ni(CO)_(4)]`

Strong field ligands like `CO, CN^(-)` generally result in inner orbital complexes.
In `[Ni(H_(2)O_(6)]^(2+), H_(2)O` is a weak field ligand, pairing of electrons will not TAKE place. Hence `[Ni(H_(2)O)_(6)]^(2+)` is PARAMAGNETIC in NATURE.
Discussion
20443.

Two electrolytic cells containing silver nitrate solution and copper sulphate solution are connected in series. A steady currrent of 2.5 ampere was passed through them till 1.078 g of Ag were deposited. How long did the current flow? What weight of copper will be deposited? (At mass of Ag=107.8, Cu=63.5)

Answer»

Solution :For DEPOSITION of Ag, reaction is: `Ag^(+) +e^(-)toAg `
Thus, 1 mole, i.e., `107.8g` Ag is DEPOSITED by 1F=96500C
`therefore1*078`g Ag will be deposited by `(96500)/(107*8)xx1*078C=965C`
Now `Q=Ixxt ""thereforet=(Q)/(I)=(965)/(2.5)=385s=6"min "26S`
For deposition of CU, the reaction is `Cu^(2+)+2etoCu`
Thus, `2F=2xx96500C` deposit Cu=1 mole=63.5 g
`therefore965C` will deposit `Cu=(63.5)/(2xx96500)xx965=0.3175g`
Discussion
20444.

Which of the following reactions give RCONH_(2)

Answer»

`R-C-=N+H_(2)Ooverset(HCL)RARR`
`RCOONH_(4)overset("heat")rarr`
`R-COCl+NH_(3)rarr`
`(RCO)_(2)O+NH_(3)rarr`

Solution :
Discussion
20445.

What are isotonic solutions ?

Answer»

Solution :The solutions having same OSMOTIC pressure are CALLED ISOTONIC solutions.
Discussion
20446.

What is the equivalent mass of a metal having electrochemical equivalent of 3.4xx10^(-7) kg?

Answer»

`32.81 XX 10^(-2) KG `
`3.281 xx 10^(-2)` kg
`3281 xx 10^(2) kg `
`328.1 xx 10^(-2)` kg

SOLUTION :`E=Z xx 96,500 = 3.4 xx 10^(-7)xx96,500 = 3.28 xx 10^(-2) Kg`
Discussion
20447.

When Cl_2 is passed through hot NaOH, oxidation number of Cl changes from

Answer»

`-1 "to" 0
0 to-1
0 to+7
0 to+5

Solution :`3 OVERSET(0 )CI_2 + 6 Na OH(h o t) to 5Naoverset(-1)CI+ Na overset(+5)CI O_3+3H_2O`
Discussion
20448.

The solution of the compound, K_(4)Fe(CN)_(6) will not given the tests of …… and …… ions.

Answer»

SOLUTION :`FE^(2+) and CN^(-)` IONS
Discussion
20449.

ZnO can be reduced to the metal byheating with carbon but not Cr_(2)O_(3).Justify your answer.

Answer»

SOLUTION :Carbon has more AFFINITY for oxygen than zinc,whereas chromium has HIGHER affinity for oxygen than zinc.Hence ZnO can be reduced to the metal by heating with carbon but not`Cr_(2)O_(3)`
Discussion
20450.

Which is most easily oxidised and possess more reactivity for nucleophilic addition:

Answer»

Methanal
Ethanal
Propanal
Propanone

Answer :A
Discussion