Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

Zeifler-Natta catalystic system is a combination of :

  1. $Rh(Ph _{3}P) _{3}CI$ and $H _{2}$
  2. $Ti(O^{i}Pr) _{4}$ and $^{t}BuOOH$
  3. $Rh(Ph _{3}P) _{3}CI$ and $CO$
  4. $TiCI _{4}$ and $AI(C _{2}H _{2}) _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ziegler-Natta catalysts are organometallic compounds used for polymerization of olefins. The classical Ziegler-Natta catalyst combines TiCl4 (titanium tetrachloride) with Al(C2H5)3 (triethylaluminum, often written as AlEt3). Option D correctly shows this combination, though the formula notation has typographical issues with subscript formatting. B and C show different catalyst systems (Wilkinson's catalyst with CO/H2, and titanium isopropoxide with tert-butyl hydroperoxide for epoxidation).

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

Monomers of Natural Rubber and Neoprene are Respectively : 

  1. $CH _3 - \underset{CH _3}{\underset{|}{C}} = CH - CH _3 , \, \, CH _3 - \underset{Cl}{\underset{|}{C}} = CH - CH _3$
  2. $CH _2 = \underset{CH _3}{\underset{|}{C}} - CH = CH _2$ $CH _2 = \underset{Cl}{\underset{|}{C}} - CH = CH _2$
  3. $CH _2 = CH - CH = CH _2$ , $CH _2 = CH - Cl$
  4. $CH _2 = \underset{Cl}{\underset{|}{C}} - CH = CH _2$ $CH _2 = \underset{CH _3}{\underset{|}{C}} - CH = CH _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

CH2=C|CH3−CH=CH2monomerofneutralrubberCH2=C|CH3−CH=CH2monomerofneutralrubber             CH2=C|Cl−CH=CH2monomerofneoprene

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

Polymerisation may occur through intermediate formation of___________.

  1. carbocations

  2. carbanions

  3. free radicals

  4. carbenes
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization like free radical electrophilic and nucleophile polymerisations through the formation of free radicals, carbanions and carbocation intermediates. Carbene doesn't form in the reaction mechanism as intermediate.
Hence, options A, B and C are correct.

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

State True or False.

The presence of double bonds in rubber molecules influence their structure and reactivity.

  1. True

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

The given statement is true.
The presence of double bonds in rubber molecules influence their structure and reactivity.
In natural rubber, double bonds have cis configuration. Hence, the chains do not come closer this results in weak intermolecular attractions. Natural rubber has coiled structure, it is elastic and non-crystalline. 
In gutta-percha(synthetic rubber) double bonds have trans configuration. The zig-zag chains pack more closely. It is highly crystalline, non elastic, hard & brittle.

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

The basis on the mode of their formation, the polymers can be classified:

  1. As addition polymers only

  2. As condensation polymers only

  3. As copolymers

  4. Both as addition and condensation polymers
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

On the basis of the mode of their formation, the polymers can be classified as addition polymers and condensation polymers.
Addition polymers are formed by chain growth polymerization and condensation polymers are formed by the combination of two monomers by the elimination of a small molecule like water or methyl alcohol.


Option D is correct.

Multiple choice classification of polymers introduction to polymers and its classification polymer polymers chemistry

Polyethene is produced by :

  1. isomerization

  2. polymerisation

  3. hydrogenation

  4. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Polymerization is the process of reacting monomer molecules together in a chemical reaction to form polymer chains or three dimensional networks.There are many forms of polymerization like step growth and chain growth.It occurs via variety of reaction mechanisms due to functional groups present and their steric effects.