Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The number of moles of oxygen obtained by the electrolytic decomposition of 108 g water is

  • 2.5

  • 3

  • 5

  • 7.5


B.

3

2H2Electrolysis 2H2 + O2

2mol                              1mol

2 x 18 = 36 gm

Since, 36 gm of H2O produce 1 mole of oxygen.

 108 gm of water will produce oxygen = 10836= 3 mol


12.

The pH of a 0.001 M solution of HCl is

  • 0

  • 3

  • 5

  • 10


B.

3

pH of 0.001 M solution of HCl is 3.

[H+] = 0.001

pH = -log [H+]

     = -log [10-3]

     = 3


13.

A fruity smell is produced by the reaction of C2H5OH with

  • CH3COCH3

  • CH3COOH

  • PCl5

  • CH3CHO


B.

CH3COOH

C2H5OH reacts with CH3COOH and gives ethylethanoate. It is an ester and has fruity smell.

C2H5OH + CH3COOH conc. H2SO4 CH3COOC2H5 + H2O

                                                        Ester


14.

The set representing the correct order for first ionisation potential is

  • K > Na > Li

  • Be > Mg > Ca

  • B > C > N

  • Ge > Si > C


A.

K > Na > Li

The ionisation potential decreses in group on moving downward because atomic radius increases hence, the correct order is

Be > Mg > Ca


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15.

Bleaching powder is obtained by treating Cl2 with

  • Ca(OH)2

  • CaO

  • CaCO3

  • CaCl2


A.

Ca(OH)2

Bleaching powder is obtained by treating Cl2 with lime water.

Ca(OH)2 + Cl2  CaOCl2 + H2O


16.

The hybridisation state of carbon in fullerene is

  • sp

  • sp2

  • sp3

  • sp3d


B.

sp2

The hybridisation state of carbon in fullerene is sp2.


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17.

Solubility product of PbCl2 at 298 K is 1 x 10-6. At this temperature solubility of PbCl2 in mol/L is

  • (1 x 10-6)1/2

  • (1 x 10-6)1/3

  • (0.25 x 10-6)1/3

  • (2.5 x 10-6)1/2


C.

(0.25 x 10-6)1/3

 PbCl2Pb2+s + 2Cl-2s

KSP = (S) (2S)2

1 x 10-6 = 4S3

S = 14×10-61/3 = (0.25 x 10-6)1/3

Therefore, temperature solubility of PbCl2 in mol/L is (0.25 x 10-6)1/3


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18.

Plaster of paris is

  • CaSO4.12H2O

  • CaSO4.2H2O

  • CaSO4.H2O

  • CaSO4.4H2O


A.

CaSO4.12H2O

Calcium sulphate hemihydrate (CaSO4.12H2O) is called plaster of paris.


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19.

When dihydroxy acetone reacts with HIO4, the product is/ are

  • HCHO

  • HCOOH

  • HCHO and HCOOH

  • HCHO and CO2


D.

HCHO and CO2

When dihydroxy acetone reacts with HIO4, products formed are HCHO and CO2.


20.

Heavy water is

  • CaSO4

  • water contain CaSO4, MgSO4

  • D2O

  • water contain CaCO3


C.

D2O

D2O is called heavy water. It is used as moderator in nuclear reactor.


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