Grade 7 Pre-technical – Non-Metallic materials Quiz
1. What is a non-metallic material?
Non-metallic materials (like wood, plastic, ceramics) generally do not show metallic properties such as good electrical conductivity, shiny metal luster or being easily hammered into thin sheets (malleable).
2. Which of the following is a ceramic material commonly used for pots and tiles?
Clay fired into pottery becomes a ceramic. Ceramics (pots, tiles) are hard, brittle and heat resistant, unlike metals, rubber or cloth.
3. Which of these is a natural non-metallic material that comes from plants?
Cotton is a natural fibre grown from plants. Glass is made from sand (mineral), stainless steel is a metal, and PVC is a synthetic plastic from petroleum.
4. Which property is typical of many non-metallic materials?
Many non-metals (plastics, wood, ceramics, rubber) are electrical insulators and do not conduct electricity well, unlike metals.
5. Which of the following is an example of a thermoplastic?
Polyethylene is a thermoplastic that softens on heating and can be remoulded. Bakelite is a thermoset (does not remelt), and porcelain/ceramic are not plastics.
6. Which material is commonly used to make clear, lightweight water bottles and is widely recycled?
PET is the clear plastic used for many drink bottles; it is light and commonly recycled. Iron, leather and wood are not used for disposable clear bottles.
7. Which manufacturing process is often used to make plastic toys and school items?
Injection moulding forces melted plastic into moulds to form toys and many plastic items. Forging, welding and annealing are metalworking processes.
8. Which non-metallic material is elastic and often used for tyres, tubes and rubber bands?
Natural rubber is elastic and stretches back to its original shape, so it is used for tyres, inner tubes and rubber bands. Porcelain, glass and copper are not elastic in this way.
9. Why should we avoid burning plastic waste at home?
Burning plastics releases toxic fumes (dioxins and other harmful gases) that can harm health and the environment. Plastics do not safely compost or turn into water or glass when burned.
10. Which non-metallic material is commonly used to insulate electrical wires?
PVC is an electrical insulator used as coating around copper or aluminium conductors in cables to prevent shocks. Aluminium, copper and gold are metals and are used as conductors, not insulators.
11. Which of the following describes ceramics used for tiles and pottery?
Ceramics are hard and brittle (they break rather than bend) and resist high temperatures, making them suitable for tiles and pottery. They are not elastic or good electrical conductors.
12. Which statement is generally true about non-metallic materials?
Most non-metals (wood, plastic, glass, ceramics) are not magnetic. Some metals (iron) are magnetic. Not all metals are magnetic, but a simple classroom test is that non-metals are usually not attracted to magnets.
13. What is plywood made from?
Plywood is made by gluing thin layers (veneers) of wood with the grain of each layer at right angles to the next. This gives strength and is commonly used in furniture and school projects.
14. Which of these is an example of a composite non-metallic material?
Fibreglass combines glass fibres and a plastic resin to make a strong, light composite. Aluminium is a metal, glass alone is not a composite, and cotton is a natural fibre.
15. Which non-metallic material is transparent and commonly used for windows?
Glass is transparent and used for windows and jars. Copper is a metal, rubber is opaque and elastic, and concrete is a building material but opaque.
16. Which fibre is a synthetic material made from petroleum and used in many clothes?
Polyester is a man-made (synthetic) fibre produced from petrochemicals and widely used in clothing. Wool, silk and cotton are natural fibres from animals or plants.
17. Which of the following non-metallic materials is biodegradable (breaks down naturally)?
Wood is a natural material that can decompose over time with the help of microbes, making it biodegradable. Plastics, glass and ceramics do not break down easily in nature.
18. What do we call plastics that can be heated, softened and reshaped many times?
Thermoplastics soften when heated and can be reshaped and recycled by remelting. Thermosetting plastics set permanently and do not remelt after curing.
19. Which adhesive is most suitable for joining pieces of wood when making school furniture?
PVA glue is made for woodworking, gives a strong bond for furniture, and is easy to use at school. Solder and welding are for metals; nails can be used but PVA gives a better glued joint.
20. Which environmental factor can cause many plastics and fabrics to weaken or fade over time?
UV rays from sunlight break down many polymers and dyes, causing plastics and fabrics to become brittle or faded. Magnetism, batteries and noise do not directly cause that damage.
21. What is MDF (medium-density fibreboard) made from?
MDF is produced by breaking wood into fibres, combining with glue, and pressing into boards. It is commonly used in furniture and school projects.
22. Which finishing treatment gives wooden furniture a shiny protective surface?
Varnish is a liquid finish that dries to form a hard, protective and often shiny surface on wood. Galvanising and soldering are metal treatments, and magnets do not harden wood.
23. How can many plastics be recycled for new products?
Many thermoplastic materials can be collected, cleaned, melted and remoulded into new items. Dissolving in water or burning produces pollution or does not create usable material.
24. Why are ceramic materials used in electrical appliance plugs and sockets?
Ceramics do not conduct electricity and can withstand high temperatures, making them safe choices for parts near heat and live wires. They do not stretch, conduct electricity, or have magnetic properties.
25. Which non-metallic material would be most suitable as the top surface of a hotplate because it resists high temperatures?
Ceramics resist high heat and are often used on surfaces that get very hot. Plastic, cotton and rubber would melt, burn or be damaged at hotplate temperatures.