Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

31.

PCl5 C2H5Cl, Y PCl5 CH3COCl

X and Y are

  • (C2H5)2O and CH3CO2H

  • C2H5I and C2H5CHO

  • C2H5OH and CH3CO2H

  • C2H5OH and C2H5CHO


C.

C2H5OH and CH3CO2H

X and Y are C2H5OH and CH3CO2H.

C2H5OH PCl5 C2H5Cl + POCl3 + HCl

CH3CO2PCl5 CH3COCl + POCl3 + HCl


32.

Keto - enol tautomerism is not observed in

  • C6H5COC6H5

  • C6H5COCH=CH2

  • C6H5COCH2COCH3

  • CH3COCH2COCH3


A.

C6H5COC6H5

C6H5COC6H5 does not exhibit tautomerism as it contains no α- H-atom.


33.

Vitamin C is

  • citric acid

  • lactic acid

  • paracetamol 

  • ascorbic acid


D.

ascorbic acid

Vitamin C is chemically known as ascorbic acid. 


34.

For which element the inertness of the electron pair will not be observed? 

  • Sn

  • Fe

  • Pb

  • In


B.

Fe

Inert pair effect is exhibited only by heavy metals of p-block elements. 


35.

Radioactivity of a sample (Z = 22) decreases 90% after 10 yr. What will be the half-life of the sample? 

  • 5 yr

  • 2 yr

  • 3 yr

  • 10 yr


C.

3 yr

t = 10 year, t12 = ?

λ = 2.303t log N0Nt 

( radioactivity decreases 90% in 10 year)

∴ N0 = 100 and Nt = 10

Thus, 

λ = 2.30310  log 10010

   = 2.30310

Since, t1/30.693λ

t1/20.693 × 102.303 = 3 years


36.

When AgCl is treated with KCN

  • Ag is precipitated

  • a complex ion is formed

  • double decomposition takes place

  • no reaction takes place


B.

a complex ion is formed

When AgCl is treated with with KCN, a complex ion is formed.

AgCl + 2KCN → K[Ag(CN)2] + KCl


37.

Which one of the following is an example of co-polymer?

  • Buna-S

  • Teflon

  • PVC

  • Polypropylene


A.

Buna-S

Among all the given options, Buna-S is the correct option. It is an example of co-polymer of butadiene and styrene.

-(CH2 - CH = CH - CH2 - C|C6H5H - CH2)n-


38.

Which one of the following produced when acetone is saturated with HCl gas?

  • Acetone alcohol

  • Phorone

  • Mesityl oxide

  • Benzene


C.

Mesityl oxide

Mesityl oxide is produced when acetone is saturated with HCl gas. 

2CH3COCH3 HCl (g) CH3COCH=C(CH3)2 + H2O


39.

Boiling water reacts with C6H5N2+Cl- to give

  • aniline

  • benzylamine

  • phenol

  • benzaldehyde


C.

phenol

Boiling water reacts with C6H5N2+Cl- to give phenol.

C6H5N2+Cl- BoilH2O C6H5OH (SNAr mechanism)


40.

Which of the following metals has the largest abundance in the earth's crust? 

  • Aluminium

  • Calcium

  • Magnesium

  • Sodium


A.

Aluminium

Aluminium is the most abundant metal and third most abundant element in earth's crust.