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Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Bayer's reagent is

  1. $Br _{2}/CCl _{4}$
  2. Cold, dilute alkaline $KMnO _{4}$
  3. Acidified $KMnO _{4}$
  4. $O _{3}/Zn/H _{2}O$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bayer's reagent is defined as a cold, dilute, alkaline solution of potassium permanganate (KMnO4). It is used to test for unsaturation in organic compounds, where it turns from purple to brown.

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Acidity of fluoroform (I), bromoform (II), iodoform (III) and chloroform (IV) in decreasing order is as follows:

  1. I> II> III> IV

  2. IV> III> II> I

  3. IV> I> II> III

  4. IV> I> III> II
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The acidity of haloforms depends on the stability of the conjugate base (carbanion). The stability follows the order of electronegativity of the halogen: F > Cl > Br > I. Thus, the acidity order is fluoroform > chloroform > bromoform > iodoform (IV > I > II > III).

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Which of the following is used in paint removing ?

  1. $CHCl _{3}$
  2. $CH _{2}Cl _{2}$
  3. $CCl _{4}$
  4. $CH _{3}Cl$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$CHCl _3$ is used as solvent and as an anaesthetic.

$CCl _4$ is used as a fire extinguisher.
$CH _2Cl _2$ is used as paint removing.
$CH _3Cl$ is used as a refrigerant.

Hence, the correct option is B.

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Carbon tetrachloride is inflammable. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbon tetrachloride (CCl4) is non-flammable and has historically been used as a fire extinguishing agent. Therefore, the statement that it is inflammable is false.

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Chocolates and fatty foods containing butter or oil sometimes leave stains on clothes that are difficult to remove. They can be removed by:

  1. a solution of salt in water

  2. tetrachloroethylene

  3. water

  4. alcohol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chocolates and food strains can be removed by tetrachloroethylene. It is a colourless liquid widely used for cleaning of fabrics and therefore called 'Dry-Cleaning fluid'.

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Dehydrohalogenation of alkyl halides is a common preparation method of:

  1. alkenes

  2. alkanes

  3. haloalkenes

  4. both A and B
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dehydrohalogenation is an organic reaction in which alkyl halide when boiled with alcoholic alkali gives corresponding alkene. It is known as elimination reaction.

Multiple choice polyhalogen compounds haloalkanes and haloarenes chemistry

Alkaline hydrolysis of 1,1,1-trichloro derivative (A) of an alkane gives a molecule (B) which produces red coloration with aqueous ${ FeCl } _{ 3 }$. The compound (A) is ?

  1. ${ CH } _{ 3 }{ CH } _{ 2 }{ CCl } _{ 3 }$
  2. ${ CH } _{ 3 }{ CCl } _{ 3 }$
  3. ${ CH }{ Cl } _{ 3 }$

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Alkaline hydrolysis of a trichloro derivative will give a carboxylic acid. The carboxylic acid that gives red colouration with aqueous $FeCl _{3}$ is acetic acid $CH _{3}COOH$. Hence, the compound  A is $CH _{3}CCl _{3}$.
Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Heating rubber with sulphur is known as:

  1. galvanization

  2. bessemerisation

  3. vulcanization

  4. sulphonation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The formation of vulcanised rubber-

To improve these physical properties,
  • water repelent
  • Less water absorption
  • Resist for oxidising agents
  • Strength
 a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K.On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened, The correct option is [C].

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

In vulcanization of rubber :

  1. sulphur reacts to form a new compound

  2. sulphur cross-links are introduced

  3. sulphur forms a very thin protective layer over rubber

  4. all statements are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Vulcanisation of rubber-

To improve these physical properties,
  • Strength
  • Resistance for oxidation
  • Repulsion from water
 a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between $373 K to 415 K.$ On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened.

The correct option is [B].

Multiple choice chemistry polymer synthetic rubber rubber manmade materials

Sulphur is used in  the vulcanization of rubber.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vulcanization is a chemical process for converting natural rubber into a more durable material by adding sulphur or other equivalent curatives. This process creates cross-links between polymer chains.