VII. Nickel. (Read the text and say about nickel applications.)

One of the most useful metals, nickel makes up 0.007 percent of the Earth's crust. It is silvery, lustrous, hard, malleable, and magnetic. In 1751 Axel F. Cronstedt, a Swedish chemist, first isolated the element.

Pure nickel is used in coatings (nickel plate) on other metals to embellish or protect them. The coat is applied by electroplating. Nickel alloys have numerous domestic and industrial applications. Copper, zinc, and nickel form a metal known as German silver, used to make tableware and as a base for silver-plated ware. Nickel alloyed with copper is used to make coins.

Most nickel is used as a strengthener in the manufacture of steel. To reduce costs and increase toughness, it is often alloyed with chromium. Nickel-chromium steel (which is resistant to corrosion, oxidation, and heat) is used in high-strength structures; heat-treated machine parts; automobile axles, shafts, and gears; and in armour plate. Copper-nickel alloys are used for bullet jackets and boiler tubes. Electrical-resistance wire in electric appliances is usually an alloy of nickel with other metals– iron, chromium, or copper.

Nickel compounds have many uses: nickel oxide is used in storage batteries, glassmaking, and pottery glazes. Nickel salts are used in electroplating and for hardening oils in soap and margarine. Nickel resists the action of most acids except nitric acid.

VIII. Plastics. (Read the text and make its grammar analysis.)

It would be difficult to imagine a world without plastics. Among the most versatile materials ever developed, plastics can be made to resemble and even replace such diverse materials as metal, wood, glass, china, stone, cloth, rubber, jewels, glue, cardboard, varnish, and leather. The word plastic comes from the Greek plastikos, meaning "mouldable" or "formable." When heated to a liquid or semi-solid form, plastics can be moulded into almost any desired shape; when cool they harden into a solid.

As many as 50 or more different types of plastics exist, with new ones being developed as research continues. Different plastics are used for different purposes, but most of them tend to be strong, durable, lightweight, and resistant to corrosion. They are often less expensive than other materials and can be made in a wide variety of colours.

Plastics also serve as good electrical or heating insulators. Their versatility, durability, and low cost make them ideal materials for wide use in industry and in craftwork. Also for the same reasons plastics have replaced metal, wood, glass, and other materials in many applications.

Many common, and not-so-common, plastic items produced by industry have found their way into nearly every line of business. For instance, plastics are frequently substituted for objects originally made of metal because of their light weight and resistance to rust. More automobile parts, such as headlights, bumpers, and side panels, are being made of plastic. Radio, television, and computer cabinets can be moulded entirely of plastic. Protective helmets of all sorts – football, baseball, construction, and even combat helmets – are made of plastic. The light weight and strength of plastics have made them essential to the aerospace industry.

Glasslike plastics are made into lenses, reflectors, costume jewellery, dentures, artificial eyes, soft-drink bottles and milk bottles, decorative murals, and moving parts in appliances, automobiles, and business machines. Plastic resins are used to make wet proof bags, wool that will not shrink, and collars that stay starched.

Plastics also can be made into disposable diapers; plates, cups, eating utensils, and non-stick cookware; coatings and adhesives; construction products; and clothing. Polystyrene, a snow like foamed plastic, is popular not only with manufacturers but also with handicrafters for making novel, decorative items. The list is a long one, and new uses are found for plastics, it seems, day by day.