Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

36 g water and 828 g ethyl alcohol form an ideal solution. The mole fraction of water in it, is :

  • 1.0

  • 0.7

  • 0.4

  • 0.1


D.

0.1

Number of moles of water (n) = 3618 = 2

No. of moles of ethyl alcohol (N) = 82846 = 18

 Mole-fraction of water = nn+ N 

22 + 18 = 220 = 0.1


12.

PCl5 was heated in a 10 dm3 container at 250°C

PCl5(g)  PCl3(g) + Cl2 (g)

0.1 mol PCl5 and 0.2 mol Cl2 was found at equilibrium. The equilibrium constant for the reaction is :

  • 0.025

  • 0.04

  • 0.02

  • 0.05


B.

0.04

PCl   PCl3 + Cl2

a            0        0

(a-x)      0.2      0.2(in equil)

0.1 mol  mol      mol

Hence, Kc[PCl3][Cl2][PCl5] = 0.210×0.2100.110

= 0.04


13.

In the reaction,

H2SO4 + H2 H3O+ + HSO4-,

the conjugate acid of water is :

  • H3O+

  • H2O

  • HSO4-

  • SO42-


A.

H3O+

The conjugate acid of water is H3O+


14.

What will be the main product, when benzene vapours are passed over V2O5 at 450°C ?


B.

Maleic anhydride is obtained by the oxidation of benzene in the presence of V2O5 at 450°C .

2C6H6 + 9O2 450°CV2O5 ( maleic anhydride) + 4H2O +CO2


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15.

Poisonous gas 'Lewisite' is obtained by the reaction of :

  • CHCH and AsCl3

  • CH2=CH2 and AsCl3

  • CHCH and S2Cl2

  • CH2=CH2 and NOCl


A.

CHCH and AsCl3

Poisonous gas 'Lewisite' is obtained by the reaction of AsCl3 with acetylene

CHCH + AsCl3  CHCl=CH-AsCl2Lewisite


16.

Hydrogen in respect to chlorine, is :

  • electropositive

  • electronegative

  • neutral

  • none of the above


B.

electronegative

Chlorine is more electronegative (electronegativity = 3.0) than hydrogen (2.1). Hence, hydrogen is electropositive in respect to chlorine.


17.

Which of the follownig elements, is most electronegative ?

  • F

  • O

  • Ne

  • Na


A.

F

Fluorine is the most electronegative element of the periodic table. Its electronegativity is 4.0.


18.

What is obtained , when propene is treated with N-bromo succinimide ?

  • CH3-CBr=CH2

  • BrCH2-CH=CH2

  • BrCH2-CH=CHBr

  • BrCH2-CHBr-CH2Br


B.

BrCH2-CH=CH2

Propene reacts with N-bromo succinimide to give allyl bromide , as the allyl hydrogen is comparitively easier to be replaced than vinyl hydrogen .


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19.

Phenolphthalein is not suitable for the titration of :

  • NaOH vs (COOH)2

  • KOH vs H2SO4

  • K2CO3 vs HCl

  • none of the above


C.

K2CO3 vs HCl

Phenolphthalein indicator is suitable for the titration of strong base vs. strong acid and strong base vs. weak acid. Here, NaOH, KOH are strong bases and K2CO3 also give strong base (KOH) in solution. Hence, phenolphthalien is suitable for each titration.


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20.

For a gaseous reaction,

C2H4 + H2  C2H; H = -32.7 Kcal.

The concentration of C2H4 can be decreased by :

  • increasing pressure

  • increasing amount of H2

  • decreasing temperature

  • all of these


D.

all of these

C2H4 + H2  C2H6 + 32.7 Kcal

In this reaction, volume is decreasing and heat is evolving. Hence, according to Le-Chatelier principle, we have to increase pressure, decrease temperature and increase concentration of H2 to make the reaction proceed in forward direction.


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