Free Synthetic Fibres and Plastics 02 Practice Test - 8th Grade
Question 1
Which of the following fibres are made from petrochemicals?
SOLUTION
Solution : A and C
∙ Fibres are obtained either from natural or artificial sources.
∙ Nylon and polyester are synthetic fibres obtained from chemical sources like petrochemicals.
∙ Jute and cotton are natural fibres obtained from jute and cotton plants respectively.
Question 2
Fabrics made from which of the following fibres do not wrinkle easily?
SOLUTION
Solution : B and D
Fabrics made from polyester or acrylic are widely used in pants, shirts, suits and bedsheets either by itself or as a blend. This is because of their wrinkle resistant and shape retention properties.
Question 3
Which of the following are properties of plastics?
SOLUTION
Solution : A and B
Plastics are widely used as they are lightweight, water-resistant, durable, strong, economical, resistant to corrosion and chemicals.
Plastics have many disadvantages too. They are non-biodegradable, so will remain on the earth's surface without being decomposed. Thus, they contribute greatly to environmental pollution.
Question 4
Which of the following are the properties of plastic?
Non-reactive, non-conductive.
Strong, durable, heavy.
Strong, durable, light.
Weak, durable, heavy.
SOLUTION
Solution : A and C
Plastics are light, strong and durable. They are also non-reactive towards chemicals. They are poor conductors of heat and electricity, cheap and easy to handle. Because of all these properties, plastics are used in making a wide variety of products.
Question 5
Sweaters knitted of acrylic keep us as warm as woollen sweaters.
True
False
SOLUTION
Solution : B
Many of the sweaters and shawls are made of synthetic fibre called acrylic. Acrylic is a synthetic fibre which resembles wool. However, acrylic sweaters are not as good insulators as woolen sweaters. Hence, acrylic seaters are unsuitable for very cold temperatures.
Question 6
Fibres of _______ resemble that of silk and hence, it is popularly known as 'artificial silk'.
SOLUTION
Solution : B
Rayon was developed as an alternative for silk. It is prepared by the chemical processing of wood pulp or cellulose. It resembles the texture and look of natural silk and can be woven like silk fibres. Hence, it is also called artificial silk.
Question 7
Firefighters' uniform is coated with a plastic that is fire resistant. Identify the plastic from the given options.
Teflon
Polyester
PET
Melamine
SOLUTION
Solution : D
Melamine is a versatile material which resists the spread of fire. It can tolerate heat better than other plastics. It is used in the firefighters' uniforms for the protection of their body from heat hazards. It is also used for making floor tiles, kitchenware, in aeroplanes and buses to prevent the spread of fire.
Question 8
Identify the type of plastic that can best be used to make electrical switches.
SOLUTION
Solution : D
Bakelite is a thermosetting plastic, which means it retains its shape even at high temperatures. Whereas, the others mentioned are thermoplastics that can be moulded on heating.
Also, bakelite is a poor conductor of electricity, hence, it protects us from getting electric shocks.
This is the reason, bakelite is used for making electrical switches, handles of various utensils, etc.
Question 9
Which one of the following is a thermosetting plastic?
SOLUTION
Solution : B
Thermosetting plastics are those plastics which once moulded, cannot be softened by heating. Two examples are:
1) Bakelite: Used for making electrical switches, handles of various utensils.
2) Melamine: Used for making floor tiles, kitchenware and fabrics which can resist heat.
Question 10
Which amongst the following pair of fibres are made artificially?
SOLUTION
Solution : A
Fibres that are obtained from chemical substances are called as man-made fibres or synthetic fibres. For example, nylon, polyester, etc.
However, silk and jute are natural fibres.