21.

In which part of the atmosphere, does the freon remain unchanged?

• Stratosphere

• Troposphere

• Mesosphere

• Thermosphere

Addition of which of the following reagents to alkene is stereospecific:

I.Br₂          II. KMnO₄

III. BH₃ THF/H₂O₂.NaOH

Select the correct reagent:

• Both I and II

• Both II and III

• Both I and III

• I, II and III

Which of the following is the correct increasing order of stability of free radicals.

• (CH₃)₂CH⁰ < (CH₃)₂CH⁰ < (C₆H₅)₂⁰CH < (C₆H₅)₃C⁰

• (CH₃)₂CH⁰ < (CH₃)₂C⁰ < (C₆H₅)₃⁰C < (C₆H₅)₂C⁰

• (C₆H₅)₃⁰C < (C₆H₅)₂⁰CH < (CH₃)₃⁰C < (CH₃)₂⁰CH

• (C₆H₅)₂⁰CH < (C₆H₅)₂C⁰ < (CH₃)₃⁰C < (CH₃)₂⁰CH

The number of enantiomers and mesa forms for the compound , 

HOOC-CH(CH₃)-CHOH-CHBr-CHOHCH(CH₃)-COOH are respectively:

• 12 , 2

• 12 , 4

• 8 , 4

• 8 , 2

Which of the following yields as a major product is mono chlorination of ethyl benzene in the presence of light and heat.

• m- chlorotoluene

• a mixture of -O- and p-chlorotoluene

• 1-chloro-2- phenylethane

• 1-chloro -1- phenyl ethane

The correct IUPAC name of

• 4-methyoxy -2- nitrobenzaldehyde

• 4-formyl -3- nitro anisole

• 4- methoxy -6- nitrobenzaldehyde

• 2-formyl -5- methoxy nitrobenzene

An unknown silver salt of monoacidic alkyne contains 67.08% silver. The structure of the alkyne is:

• ${\mathrm{CH}}_3-\mathrm{C}\equiv \mathrm{CH}$

• ${\mathrm{CH}}_3-\mathrm{C}\equiv \mathrm{CH}-{\mathrm{CH}}_3$

• ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{C}\equiv \mathrm{CH}$

• $\mathrm{CH}\equiv \mathrm{CH}$

In which of the following structure the number of shared O-atom per tetrahedrom is two and half?

• Pyroxene chain silicate

• Amphibole chain silicate

• Cyclic silicate

• Sheet silicate

Which of the following statement is not true about homolytic cleavage?

• In homolytic cleavage the movement of a single electron takes place instead of an electron pair.

• The organic reaction which proceed through homolytic bond cleavage are called ionic reactions or polar reactions

• Homolytic cleavage results in the formation of neutral species which contains an unpaired electrons

• None of the above

Hydrolysis of (CH₃)₂SiCl₂ and CH₃SiCl₃ leads to:

• linear chain and cross linked silicones respectively

• cross linked and linear chain silicones respectively

• linear chain silicones only

• cross linked silicones only