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8251.

The space model which is obtained by joining the points representing various bonded atoms gives the shape of the molecule. The geometry of the molecule is definite relative arrangement of the bonded atoms in a molecule. The shape and geometry of a molecule is explained by valence shell electron pair repulsion theory given by Gillespie and Nyholm. Which molecule has both shape and geometry identical ? (I) SnCl_(2) "" (II) NH_(3) "" (III) PCl_(5) "" (IV) SF_(6)

Answer»

I, III and IV
II,III and IV
III and IV
All

Answer :C
Discussion
8252.

The use of common salts, e.g., NaCl or CaCl_2 anhydrous is made to clear snow on the roads. This causes:

Answer»

A LOWERING in f.pt. of water
A lowering in m.pt. of ice
Ice MELTS at the temperature of atmosphere PRESENT at that time
All

Answer :D
Discussion
8253.

The space model which is obtained by joining the points representing various bonded atoms gives the shape of the molecule. The geometry of the molecule is definite relative arrangement of the bonded atoms in a molecule. The shape and geometry of a molecule is explained by valence shell electron pair repulsion theory given by Gillespie and Nyholm. Which is not the electron geometry of covalent molecules ?

Answer»

PENTAGONAL bipyramidal
Octahedral
Hexagonal
Tetrahedral

Answer :C
Discussion
8254.

Which of the following statements are correct for an electron that has n = 4 and m = -2?

Answer»

The electron may be in a p-orbital.
The electron is in the FOURTH principal ELECTRONIC shell.
The electron may be in a d-orbital.
The electron must have the SPIN quantum number = -1/2.

Solution :n = 4, m = -2 does not correspond to p-orbital (because for p-orbital, m = -1 , 0, + 1)`, but it can represent d or/orbital.
Discussion
8255.

Which of the following reagent is used to convert gt C = O "to " gt CH_(2) ?

Answer»

`ZNHG + H_(2)O`
`ZnHg + conc. HCl`
`NAHG + H_(2)O`
SN + conc. HCl

Answer :B
Discussion
8256.

Vitamin B_(12) complexcontainsthe metal :

Answer»

IRON
COBALT
Magnesium
NICKEL.

Answer :B
Discussion
8257.

Write the products of oxidation of glucose with : Bromine water

Answer»

Solution :`UNDERSET("GLUCOSE")underset(CH_(2)OH)underset("|")overset("CHO")overset("|")(("CHOH")_(4)) + [O] overset(Br_(2) - H_(2)O)to underset("Glucose acid")underset(CH_(2)OH)underset("|")overset("COOH")overset("|")(("CHOH")_(4))`
Discussion
8258.

What happens when Oxidation of acetoneoxime with trifluoroperoxy acetic acid.

Answer»

SOLUTION :Oxidation of acetoneoxime with trifluoroperoxy acid gives 2-nitropropane.
`underset(("Acetoneoxime"))(CH_(3) - underset(CH_(3))underset(|)(C) = N - OH) underset((O))overset(CF_(3)COOOH)rarr underset(("2-nitropropane"))(CH_(3) - underset(CH_(3))underset(|)(CH)-NO_(2))`
Discussion
8259.

The reducing agents to convert metal oxides to metals are carbon, carbon monoxide or even some metals.

Answer»


ANSWER :1
Discussion
8260.

Which of the following statements is/ are true? (I) Ethers are soluble in cone. H_2SO_4 but separate out on addition of water. (II) Ethers are used as solvents for BF_3 and Grignard reagent. (III) Mononitration of p-methylanisolc gives 2-nitro-4-methylanisole (IV) Monobromination ofp-ethoxyphenol gives 2-bromo-4-ethoxyphenol (V) 4-ChlorophenoI (I) will dissolve in NaOH but 4-chloro-1 -methyl benzene (II) will not. (VI) 4-Methyl benzoic (111) acid will dissolve in aq. NaHCO_(3) , but 4-methyl phenol (IV) will not. (VII) 2,4,6-Trinilrophenol (V) will dissolve in aq. NaHCO_(3)but 4-methyl phenol (VI) will not. (VIII) 4-Ethyl phenol (VII) will dissolve in aq. NaOH but ethyl phenyl ether (VI11) will not.

Answer»


Solution :(I) Water is stronger base than ether and removes proton from protonated ether, `R_2OH^(+)`
`underset("Acid"_(1))([R_(2)OH])^(+) + underset("Base"_(2))(H_(2)O) to underset("Base"_(1))(R_(2)O) + underset("Acid"_(2))(H_(3)O^(+))`
(II) Due to unshared electron pairs, ETHERS act as Lewis bases and hence easily react with Lewis acids like `BF_3` and RMgBr to form coordinated COMPOUNDS.
`(C_(2)H_(5))_(2) OVERSET(..)o + BF_(3) to (C_(2)H_(5))_(2) overset(..)o : overset(+)(BF_(3)) 2(C_(2)H_(5))_(2)overset(..)O: + RMgBr to (C_(2)H_(5))_(2)O to underset(Br)overset(R)(Mg) larr O(C_(2)H_(5))_(2)`
Note that two molecules of ether coordinate tetrahedrally with one `Mg^(2+)`
(III)
(IV)
(V) Due to -I effect of Cl, 4-chlorophenol is acidic and dissolves in NaOH, but (II) is an aryl halide and does not dissolve.
(VI) (III) is an acid and dissolves in `NaHCO_3` but (IV) is a phenol and does not dissolve.
(VII) Although (V) is a phenol, because of the presence of `(3NO_2)` group, it is exceptionally acidic (pKa=0.38). So it dissolves in `NaHCO_3`, but (VI) is a phenol (pKa= 10.17) and will not dissolve.
(VIII) (VII) is a phenol and dissolves in NaOH, but (VIII) is an ether, and does not dissolve.
Discussion
8261.

Which will form lactone on treatment with NaOH?

Answer»

`alpha`-BROMO acid
`beta`-Bromo acid
`beta-`Hydr4oxy acid
`delta`-Bromo acid

Solution :`gamma&delta` HYDROXY acid from lactone (Cyclie Exter) on HEATING.
Discussion
8262.

Which of the following pair of monomers are used in preparation of PHBV

Answer»

`beta`-hydroxy butyric acid, `beta`-hydroxy valeric acid
`beta`-hydroxy valeric acid, amino caproic acid
`beta`-hydroxy butyric acid, ADIPIC acid
lactic acid, adipic acid

SOLUTION :`CH_(3)-CH-CH_(2)-COOH +CH_(3)-CH_(2)-overset(OH)overset(|)(C)H-CH_(2)-COOH`
` to [-O-UNDERSET(CH_(3))underset(|)(C)H-CH_(2)-underset(O)underset(||)(C)-O-underset(CH_(3))underset(|)underset(CH_(2))underset(|)(C)H-CH_2-underset(O)underset(||)(C)-]`
Discussion
8263.

Two samples of DNA, A and B have melting points 340 K and 350 K respectively. This is because

Answer»

B has more GC content than A
A has more GC content than B
B has more AT content than B
both have same AT content.

Solution :Since GC base pair havingthreebH - BONDS so it ismore stablethan ATbase pairhavingtwo H - bondstherefore DNA , B has highermeltingpoint than DNA,A.
Discussion
8264.

Which of the following is least covalent hydride?

Answer»

`H_(2)O`
`H_(2)S`
`H_(2)SE `
`H_(2)TE`

ANSWER :A
Discussion
8265.

Why are substances like platium and palladium often used for carrying out electrolysis of aqueous solutions ?

Answer»

Solution :PLATINUM and palladium FORM inert ELECTRODES, i.le., they are not atacked by the ions of the electrolyre or the products of electrolysis. Hence, they are USED as electrodes for carying out the electroluysis.
Discussion
8266.

What is the unit of specific conductiivity ?

Answer»

S
`Omegam`
`S" "cm^(2)*MOL^(-1)`
`S" "m^(-1)`

SOLUTION :`S" "m^(-1)`
Discussion
8267.

Under a goven set of experimental conditions, with increase in the concentration of the reactants, the rate of a chemical reaction

Answer»

Decreases
Increases
Remains unaltered
First decreases and them increases

Solution :According to LAW of mass-action, "at a given TEMPERATURE, the rate of a reaction at a particular instant is proportional to the product of the active MASSES of the reactants at that instant raised to POWERS which are numerically equal to the number of their respective molecules in the stoichiometric equation DESCRIBING the reaction".
Discussion
8268.

Which of the following compounds exhibit cis and trans forms ?

Answer»

2- Butyne
2- Butene
2- Butanol
1- Butanol

ANSWER :B
Discussion
8269.

When a zinc rod is suspended in copper sulphate solution

Answer»

the TEMPERATURE of the solution rises
the temperature of the solution falls
the temperature of the solution remains unchanged
COPPER is deposited on zinc rod therebyincreasing its WEIGHT .

Solution :A redox REACTION is EXOTHERMIC .
Discussion
8270.

Two solutions of KNO_3 and CH_3COOH are prepared separately. Molarity of both is 0.1 M and osmotic pressures are P_1 and p_2 respectively. The correct relationship between the osmotic pressure is :

Answer»

`P_2 GT P_1`
`P_1 = P_2`
`P_1 gt P_2`
`(P_1)/(P_1 + P_2) = (P_2)/(P_1 + P_2)`

ANSWER :C
Discussion
8271.

Which one of the elements with the following outer orbital configuration may exhibit the largest number of oxidation states ?

Answer»

`3D^(5) 4S^(1)`
`3d^(5) 4s^(2)`
`3d^(2) 4s^(2)`
`3d^(3) 4s^(2)`

Answer :B
Discussion
8272.

The reagent required to convert propene to 1-propanol is

Answer»

`B_(2)H_(6)` followed by `H_(2)O_(2)//NaOH`
CONC. `H_(2)SO_(4)` followed by HYDROLYSIS with boiling water
HBr followed by hydrolysis with aqueous KOH
`Hg(OCOCH_(3))_(2)` followed by REDUCTION with `NaBH_(4)`

Answer :A
Discussion
8273.

What volume of hydrogen gas at 273K and 1atm pressure will be consumed in obtaining 21.6 g of elemental boron (atomic mass = 10.8) from the reduction of boron trichloride by hydrogen ?

Answer»

67.2 L
44.8 L
22.4L
89.6 L

SOLUTION :`2BCl_3 + underset(3 xx 22.4 L = 67.2)(3H_2) to underset(2 xx 10.8= 21.6)(2B) + 6HCL`
volume consumed = 67.2
Discussion
8274.

Transition elements containing higher oxidation number possess…. Property

Answer»

REDUCING agent
Oxidizing agent
Acidic
None of the above

Answer :B
Discussion
8275.

Which of the following radicals can bring about the highest oxidation state of a transition metal?

Answer»

`F^-`<BR>`CL^-`
`Br^-`
`I^-`

ANSWER :A
Discussion
8276.

Which of the following sequence correctly represents the decreasing acidic nature of oxides?

Answer»

`NO_2` >`CO_2` >`B_2O_3` >`BEO` > `Li_2O`
`CO_2`> `NO_2` G>`B_2O_3` > `BeO` > `Li_2O`
`Li_2O`>` BeO` >`B_2O_3` >`CO_2` > `NO_2`
`B_2O_3` > `CO_2` > `NO_2`>`Li_2O`>` BeO `

ANSWER :A
Discussion
8277.

Which of the following can be employed for the conversion of potassium manganate to potassium permanganate? A) Ozone B) Chlorine C) Electrolysis

Answer»

A, B
B, C
A, C
A, B, C

Answer :D
Discussion
8278.

Write the names and structures of the monomers of each of the following polymers : (i) Natural rubber (ii) Buna-S

Answer»

SOLUTION :(i) Monomer of natural rubber is Isoprene
`UNDERSET("2-methyl Buta-1,3-diene")(CH_3 = underset(CH_3)underset(|)C - CH=CH_2)`
(ii) Monomer of Buna-S is Buta 1,3-diene `(CH_2=CH-CH=CH_2)` and styrene `(C_6 H_5 - CH=CH_2)`. ITIS used in the manufacture of automobile tyres.
Discussion
8279.

Which of the following is not produced by human body ?

Answer»

VITAMIN
CATALYST
Enzyme
DNA

SOLUTION :Vitamin
Discussion
8280.

Which one of the following is used to make 'non stick' cookware ?

Answer»

PVC
Polystyrene
POLY(ETHYLENE TEREPHTHALATE)
POLYTETRAFLUOROETHYLENE

ANSWER :D
Discussion
8281.

When vapours of ethyl alcohol are passed over Al_2O_3, at 533 K, it forms

Answer»

1, 2 - ethanediol
Ethene
Ethanal
Ethoxy ethane

Answer :D
Discussion
8282.

Write the structure of alanine at pH =2 and pH =10.

Answer»

Solution :Alanine exists as a zwitterison (I) in aqueous solution. In presence of acid `(pH=2)`, the basic `-COO^(-)` GROUP ACCEPTS a proton to give cation (II) but in presence of a base `(pH=10)`, the acidie `-overset(N)H_(3)` group donates a proton to the base and THUS exists as an anion (III).
Discussion
8283.

Which of the following electrophilic substitution reaction represent correct product.

Answer»




SOLUTION :
Discussion
8284.

Which of the following has maximum reactivity with an electrophile E^(+) ?

Answer»

<P>Toluene
`p-CH_(3) - C_(6)H_(4) - NO_(2)`
`p - NO_(2) - C_(6)H_(4) - NO_(2)`
BENZENE

Answer :A
Discussion
8285.

Xenon reacts directly with

Answer»

`F_2`
`Br_2`
`Cl_2`
All

Solution :`XE + 2F_2 UNDERSET"673 K"OVERSET(NI)to XeF_4`
Discussion
8286.

The repeating units of PCTEF is

Answer»

`CF_(2)=CF_(2)`
`CH_(2)=CH_(2)`
`CF_(3)=CF_(3)`
`FCIC=CF_(2)`

SOLUTION :`FCIC=CF_(2)` REPEATS alternatively.
Discussion
8287.

Which of the following compounds are formed by sp^3d hybridisation

Answer»

`XeF_4`
`XeF_2`
`XeF_6`
`XeO_2F_2`

SOLUTION :
Discussion
8288.

What is homogenous catalysis? Give an example.

Answer»

Solution :A REACTION in which all the reactants and the catalyst are in the same phase is called homogeneous catalysis.
`2SO_(2(G)) + O_(2(g))overset(NO_(g))to 2SO_(3(g))`
Discussion
8289.

Which of the following aqueous solutions has highest freezing point?

Answer»

0.1 molal `A1_(2)(SO_(4))`
0.1 molal `BaCl_(2)`
0.1 molal `AlCl_(3)`
0.1 molal `NH_(4)CI`

Solution :`DeltaT_(f)= iK_(f)m`
As m = 0.1 molal for all given solutions, THUS, lower the value of i, lower will be the depression in freezing point (`DeltaT_(f)`) and higher will be the freezing point of the solution.
For `Al_(2) (SO_(4))_(3)`, i = 5
For `BaCl_(2)`, i = 3
For `AICI_(3)` , i = 4
For `NH_(4)Cl` , i = 2
Thus, 0.1 molal `NH_(4)Cl` will have highest freezing point.
Discussion
8290.

What is used to prevent food from spoiling by microorganisms like fungi or to preserve food for a long time ?

Answer»

FOOD PRESERVATIVES
Antioxidants
Food colours
Stabilizer 

SOLUTION :Food preservatives
Discussion
8291.

Which of the following statements are correct for CSBr_(3)

Answer»

It CONTAINS `CSBr_(3)` and ions `Br_(3)^(-)` ions
It contains `CSBr_(3)` and `Br^(-)` and LATTICE `Br_(2)` molecule
It is a COVALENT compound
It contains `CSBr_(3)` and `Br^(-)` ions.

Solution :(a) It contains `CSBr_(3)` and ions `Br_(3)` ions
(B) It contains `CSBr_(3)` and `Br^(-)` and lattice `Br_(2)` molecule
Discussion
8292.

Write method of preparation of urotropine and give its use.

Answer»

Solution :Hexamethylene tetramine is called urotropine. It is FORMED when formaldehyde REACTS with ammonia
`underset("Formaldehyde")(6CHCHO)+4NH_(3) to underset("Urotropine")((CH_(2))_(6)N_(4))+6H_(2)O`
It is used as antiseptic for urinary TRACT infections.
Discussion
8293.

When SO_2 gas is passed through an acidified solution of K_2 Cr_2 O_7, the solution turns ___ in colour.

Answer»

the solution BECOMES BLUE
the solution becomes colourless
`SO_2` is REDUCED
green `Cr_2(SO_4)_3` is formed

Solution :`K_2Cr_2O_7 + H_2SO_4 + 3SO_2 to K_2SO_4 + Cr_2(SO_4)_3 + H_2O`
Discussion
8294.

Write the structure of the major organci product expected from the following reaction . .

Answer»

SOLUTION :` (##KSV_CHM_ORG_P2_C15_E01_172_S01.png" WIDTH="80%">.
Discussion
8295.

Which of the statements about solutions of electrolytes is not correct?

Answer»

CONDUCTIVITY of solution depends upon SIZE of ions.
Conductivity depends upon viscosity of solution.
Conductivity does not depend upon solvation of ions PRESENT in solution.
Conductivity of solution INCREASES with temperature.

Answer :C
Discussion
8296.

What is Cogultion ?

Answer»
Discussion
8297.

Which of the following form tetrahydridoborates

Answer»

`(LI)`
`NA`
`NH_(4)^(+)`
`Ag^(+)`

SOLUTION :`LiBH_(4), NaBH_(4) , H^(-)` will reduce `Ag^(+)`
Discussion
8298.

Which of the following reagent form oxime with carbonyl compound ?

Answer»

`NH_(3)OH`
`NH_(2)OH`
`NaOH`
`CH_(2) N_(2) `

ANSWER :B
Discussion
8299.

What will be the mass (in kg) of 7.298xx10^(6) mol electrons?

Answer»


ANSWER :4
Discussion
8300.

Write the cell formulation and calculate the standard cell potential of the galvanic cell in operation of which the reaction taking place is: 2Cr(s)+3Cd^(2+)(aq)to2Cr^(3+)(aq)+3Cd(s) Calculate Delta_(r)G^(@) for the above reaction. (Given: E_(Cr^(3+)//Cr)^(@)=-0.74V,E_(Cd^(2+)//Cd)^(@)=-0.40V,F=96500" "C" "mol^(-1))

Answer»


SOLUTION :`Cr(s)|Cr^(3+)(aq)||Cd^(2+)(aq)|Cd(s)`
`2Crto2Cr^(3+)+6e^(-)` or `3Cd^(2+)+6e^(-)to3Cd`. Hence, n=6
`E_(cell)^(@)=-0.40-(-0.74)=+0.34V,Delta_(r)G^(@)=-nFE_(cell)^(@)`
Discussion