Tag: chemistry

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Questions Related to chemistry

Multiple choice chemistry animal fibre synthetic fibres & their characteristics processing of fibres synthetic fibres and its types

Which of the following is not an example of natural polymer?

  1. Wool

  2. Silk

  3. Leather

  4. Nylon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Natural polymers occur in nature and can be extracted. 


Examples of naturally occurring polymers are silk, wool, leather, DNA, cellulose and proteins. 


Synthetic polymers are human-made polymers.

Examples of synthetic polymers include nylon, polyethene, polyester, Teflon, and epoxy. 

Hence, option D is the correct option.

Multiple choice chemistry animal fibre synthetic fibres & their characteristics processing of fibres synthetic fibres and its types

The acrylic polymer must contain :

  1. acrylonitrile monomer.

  2. sodium thiocyanate.

  3. acrylic acid.

  4. sulphuric acid.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of approx 100,000, about 1900 monomer units. 


For a fiber to be called acrylic, the polymer must contain at least 85% acrylonitrile monomer. Acrylonitrile is an organic compound that is a colorless volatile liquid.

So, the correct option is $A$

Multiple choice chemistry animal fibre synthetic fibres & their characteristics processing of fibres synthetic fibres and its types

State True or False.


Teflon is natural polymer.

  1. True

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

There are two types of polymers: synthetic and natural. 


Synthetic polymers are derived from petroleum oil and made by scientists and engineers. Examples of synthetic polymers include nylon, polyethene, polyester, Teflon, and epoxy. 

Natural polymers occur in nature and can be extracted. They are often water-based. Examples of naturally occurring polymers are silk, natural rubber, wool, DNA, cellulose and proteins.

Hence, it is a false statement.

Multiple choice chemistry animal fibre synthetic fibres & their characteristics processing of fibres synthetic fibres and its types

Which of the following is not a synthetic polymer?

  1. polyvinyl chloride

  2. plastic

  3. polystyrene

  4. polyethylene

  5. cellulose
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Cellulose is not a synthetic polymer. It is a natural polymer.
It is a polysacchardie having molecular formula $(C _6H _{10}O _5) _n$. It has linear chain of $\beta(1\rightarrow 4)$ linked D-glucose units. There are several hundred to many thousands of such units in a chain.  Cellulose is an important structural component of  in the primary cell wall of green plants, many forms of algae and the oomycetes.

Multiple choice chemistry materials: metals and non-metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

Generally ornaments are usually made up of 24 karat gold.

  1. True

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

Ornaments and jewellry can't be made of 100 per cent pure gold or 24 Karat gold as it is very soft and delicate. Most of jewellry are made of 22 karat to 10 karat of gold.


24 carat is pure gold so it has less strength to make ornaments. To impart strength, some impurities are mixed such as copper to make the 22 carat gold which is suitable for making ornaments. Therefore, 24 carat gold is pure gold , it is weak to make ornaments.

Multiple choice chemistry materials: metals and non-metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

Non-metals have many different colours.

  1. True

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

Non-metals like phosphorous exist in various colors such as white, scarlet, yellow, red, violet, black. Similarly, sulfur is pale yellow, bromine is red-brown colored in liquid and vapor state.
Thus option $A$ is correct.

Multiple choice chemistry materials: metals and non-metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

Non-metals are less dense and have low melting and boiling points as compared to metals.

  1. True

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

The melting point of an element is the temperature at which it converts from solid form to a liquid. In metals, there are two types of bonding that lead to higher melting points: covalent and metallic. Covalent bonds are when electron pairs are shared equally between atoms, and they pull atoms even closer together if multiple pairs of electrons are involved. Metallic bonds involve electrons that are delocalized: they float between many atoms, not just two, and positively charged nuclei are firmly bound to the surrounding "sea" of electrons. As strong bonds between atoms give elements higher melting points, it is also true that lower melting points are a result of weaker bonds or a lack of bonds between atoms. Therefore non-metals lack metallic bonding between atoms therefore have lower melting and boiling point than metals.
Also the closed and dense packing of metals in the lattice impart them high density and strength that lacks in non-metals.
Thus option A is true.