Tag: polymer

Quizzes (7) Questions (194)

Questions Related to polymer

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Which of the following has cross-linked polymer?

  1. Vulcanised rubber

  2. Nylon

  3. Phenol-formaldehyde resins
  4. Both $A$ and $C$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Vulcanised rubber contains sulphur bridges between polymer chains, and phenol-formaldehyde resins (like Bakelite) are thermosetting polymers with a highly cross-linked structure. Both are examples of cross-linked polymers.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

In the process of vulcanization:

  1. natural rubber is heated with sulphur

  2. natural rubber is heated with carbon

  3. natural rubber is heated with phosphorous

  4. natural rubber is heated with sodium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vulcanization is a chemical process by which the physical properties of natural or synthetic rubber are improved. In its simplest form, vulcanization is brought about by heating rubber with sulfur.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Which material is used for vulcanisation of rubber?

  1. Iron

  2. Sulphur

  3. Chlorine

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

The material used for the vulcanisation of rubber is sulphur.


The reasons why the rubber is vulcanised are as follows:

i) It is soft and sticky and becomes more so at high temperature and brittle at low temperature. That is why, it is used at low-temperature range ($280-330$) K, where its elasticity is maintained.
ii) It is attacked by oxygen and other oxidising agents.
iii) It has a high water absorption capacity, low tensile strength and low resistance to abrasion.
iv) It is reactive to organic solvents.
Therefore, natural rubber is vulcanised by heating it with about ($3-5\%$) sulphur at ($373-415$) K.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Strength of synthetic fibre is better during-

  1. dry condition

  2. wet condition

  3. humid condition

  4. never
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Synthetic fibres generally maintain their structural integrity and strength better in dry conditions. Moisture can often weaken the intermolecular forces or cause swelling in certain synthetic materials.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Which of the following type of forces are present in vulcanized rubber?

  1. Weakest intermolecular forces

  2. Hydrogen bonding

  3. Three dimensional network of bonds

  4. Metallic bonding
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vulcanised rubber is highly elastic, so weakest intermolecular forces present in it.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Which of the following is resistant to petrol, lubricating oils and organic solvents?

  1. Nitrile rubber

  2. Buna - N

  3. GRN

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nitrile rubber, Buna-N, and GRN are all names for the same copolymer of butadiene and acrylonitrile. This material is known for its excellent resistance to oil, fuel, and other chemicals.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

A : A mixture of raw rubber and sulphur on heating at $373:K$ - $415:K$ gives vulcanised rubber.
R : ZnO decreases the rate of vulcanisation of rubber.

  1. both A and R are correct and R is the correct explanation of the A

  2. both A and R are correct but R is not the correct explanation of the A

  3. A is correct but R is incorrect

  4. A is incorrect but R is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Natural rubber becomes soft at high temperature (>335 K) and brittle at low temperatures (<283 K) and shows high water absorption capacity. It is soluble in non-polar solvents and is non-resistant to attack by oxidising agents. 

To improve upon these physical properties, 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.

In sulfur vulcanization of natural rubber, the types of cross-links formed largely depend on the vulcanization system. The vulcanizing agents are zinc oxide (ZnO), stearic acid, accelerators, and sulfur. Conventional ZnO, or micro ZnO, is one of the basic components of rubber compounds and acts as an activator for rubber crosslinking by sulfur or sulfur donors.

Hence, reason given is incorrect. So, option C is correct.
Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Assertion (A) : The plants yield a milky suspension of crude rubber called latex.
Reason (R) : The latex contains about $85\%$ rubber.

  1. Both A and R are correct and R is the correct explanation of the A

  2. Both A and R are correct but R is not the correct explanation of the A

  3. A is correct but R is incorrect

  4. A is incorrect but R is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The plants yield a milky suspension of crude rubber called latex.
Latex is often described as the sap of the Hevea tree, a milky sticky substance. 

The sap runs deeper inside the tree, beneath the cambium.
Latex runs in the latex ducts which are in a layer immediately outside the cambium. This highlights the skill of the tapper. 

If the cambium is cut, then the tree is damaged because the cambium is where all the growth takes place.

The latex contains about $60\%$ of rubber and $40\%$ of other substances (water, proteins etc).


Assertion (A) is correct. Reason (R) is incorrect. Option C is correct.

Multiple choice chemistry manmade materials synthetic rubber rubber polymer

Acetaldehyde can be used for making synthetic:

  1. protein

  2. perfumes

  3. rubbers

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

Acetaldehyde is primarily used as an intermediate in the manufacture of a range of chemicals, perfumes, aniline dyes, plastic and synthetic rubber, etc.

$\therefore$ Answer is option $B$ and $C$.