Read the text and answer the following questions with NO MORE THAN 2 WORDS.Why does man use metals still so much today when there are other materials, especially plastics, which are available? A material is generally used because it offers the required strength, and other properties, at minimum cost. Appearance is also an important factor. The main advantage of metals is their strength and toughness. Concrete may be cheaper, it is often used in buildings, but even concrete depends on its core of steel for strength.Plastics are lighter and more corrosion-resistant, but they are not usually as strong as metals. Another problem with plastics is what to do with them after use. Metals objects can be broken down and the metals are recycled after that but plastics can only dumped or burned.Not all metals are strong, however. Copper and aluminum, for example, are both fairly weak- but if they are mixed together, the result is an alloy called aluminum bronze, which is much stronger than either pure copper or pure aluminum. Alloying is an important method of obtaining whatever special properties are required: strength, toughness, resistance to wear, magnetic properties, high electrical resistance or corrosion resistance.The properties of a metal can be further improved by use of heat treatment which changes the properties of metals and alloys. For example, hardening is used to make metals harder. Tempering makes the softer and less brittle. Annealing is carried out to make a metal soft so that it can be machined more easily. In this way metallic materials can be produced to meet every kind of engineering specification and requirement.Methods of extracting, producing and treating metals are being developed all the time to meet engineering requirements. This means that there is an enormous variety of metals and metallic materials available from which to choose.1. Which material is used so popularly nowadays? 2. What does the word “them” in paragraph 2 refer to? 3. Which material is stronger than pure copper or aluminum? 4. What process can help change the properties of metals and alloys? 5. How many methods are developed to meet engineering requirements?

Read this passage:Many manufacturers prefer plastic as a material for containers because it can be molded into many shapes. But plastic is not very strong. It must be fused with glass or steel for strength. It is also not very durable. Even the strongest plastic can break under enough pressure. The biggest disadvantage to using plastic is that it does not decompose. While plastic can be recycled, doing so is tedious and difficult. While it may be more expensive and difficult to work with, aluminum is a much stronger building material with far greater tensile strength. It conducts electricity because it is metal. Best of all, aluminum is very easy to recycle. Even if it is thrown away, it decomposes much more quickly than most manufacturing materials.Which statement best describes how the compare-and-contrast pattern of the text supports the author's purpose?A.The passage begins by listing all the benefits of plastic and aluminum and ends by listing all the weaknesses of the two materials.B.The passage begins by describing the advantages of aluminum and ends by contrasting these with the disadvantages of plastic.C.The passage begins by describing the disadvantages of plastic and ends by explaining how aluminum has many advantages over plastic.D.The passage begins by describing the benefits of plastic and ends by comparing these benefits with the benefits of aluminum.

Read the text about Plastic and The Environment and fill in the summary below with NO MORE THAN TWO WORDS.Plastic and The EnvironmentPlastic is a material we use every day. The first plastics were made more than 100 years ago from parts of plants. Plastics are now made from oil, coal and natural gas. We are using up these things so fast that the Earth's supplies may run out. Because of this, scientists are investigating new ideas for making plastics from plants such as sweet potato, bamboo and flax.Things made from plastic can be useful for people but bad for the planet. Some plastics can last for a long time without wearing out, and can be difficult to get rid of when they are not needed. They can remain in rubbish dumps called landfill sites for hundreds of years. Landfills can be smelly, ugly, and harmful to our planet.Recycling is a good way to get rid of unwanted plastics. Recycled waste materials can be used again to make new products. This can be difficult as different types of plastic need to be recycled in different ways. Some kinds of plastics can be melted down and used to make new things such as bags and bottles. Others can be made into fibres (strands of material) for clothing.Another way to protect the environment is to use canvas bags for shopping rather than plastic ones. A lot of plastic objects can also be reused. Plastic bottles can be refilled many times, rather than throwing them away once they are empty. Unwanted plastic goods such as CDs and toys can be sold or given away to charity shops.Summary:We use plastic every day in life. People can find (1) plastic products but bad for the planet. Because of this, scientists are finding new ways of making plastics from (2) like sweet potato, bamboo or flax. Different types of plastic need to be (3) in different ways. Some kinds of bags and bottles can be remade from (4) plastics. Besides, instead of using plastic bags, (5) for shopping can be a better choice. Plus, people can sell or give away to charity shops unwanted plastic goods such as CDs and toys.

A : Above all, they are cheaper and easier to process making them a viable alternative to metals.B : Polymers are essentially a long chains of hydrocarbon molecules.C : Today polymers as strong as metals have been developed.D : Metals are today being replaced by polymers in many applications.E : These have replaced the traditional chromium-plated metallic bumpers in cars.F : Many Indian Institutes of science and Technology run special programmes on polymer science.QUESTION 13bookmark_borderSelect the correct answerWhich of the following statementscan be the first statement of the paragraph?radio_button_uncheckedFradio_button_uncheckedAradio_button_uncheckedDradio_button_uncheckedEradio_button_uncheckedD

Plastics have replaced wood, paper, glass, steel, and aluminum as the materials of choice for many common objects used today. They usually have interior mechanical properties such as stiffness, strength, and temperature resistance to the materials they have replaced. However, plastics succeed because of their low density, toughness, and design flexibility. Much of this design flexibility is due to the manufacturing processes that have been developed to shape them into simple and complex forms that would be costly or even impossible to produce with traditional materials.Moulding processes have been around for a long time and are particularly suited to making plastic parts. Most of the processes can efficiently produce plastic parts in high numbers, but even where low numbers are involved, the complexity of the required shape may reduce the cost of moulding a part in plastic over machining a part from metals.Plastics production really started in the mid-20th century. Today there are hundreds of different plastics available, each one developed to have specific characteristics to meet the requirements of different users. The list of plastics appears to be endless but they fall into two categories, thermoplastics and thermosets. Thermoplastics can be melted and recycled into new parts. Thermosets are stronger than thermoplastics but cannot be recycled into new parts and have to be disposed of in other ways. Because plastics are not naturally biodegradable and not all plastics can be recycled, there is a real problem in disposing of plastic waste.To help answer this concern, bioplastics are being developed from plant materials. It is possible to produce a mouldable “plastic” with ground-up natural cellulose, other materials, and water. Drug capsules are made from starch-based bioplastics.Summary:Plastics are used for many common objects because they are strong, stiff and have (1) to temperature. The design flexibility of plastic makes it easy to be shaped into simple and complex forms, which is more expensive or impossible to manufacture with other (2) . Moulding process is a suitable method for making plastic parts. The cost of moulding a part in plastic is cheaper than one in (3) . Plastics are divided into two (4) . Thermoplastics can be heated and recycled into new parts but thermosets have to be disposed of in other ways. To solve the problem of disposing of plastic waste (5), are produced from plant materials. Drug capsules are made from this material.

Oil and natural gas are the main raw materials which (can use) in the production of plastics.Plastics (will use) in the production of a wide range of household appliances.The car industry (may use) high-precision components in their vehicles.The majority of plastic parts (could not manufacture) using injection molding many years ago.Manufacturers (could not make) make plastics to a high standard of quality before they started to use oil.Soon plastics (will make) from any kind of plant material.