Question

Questionl: Explain four basic classes of solid materials MCQ Question 2: Which of the following is true for polymers? a) They have very high molecular mass b) They do not have linear stress-strain curve c) They have high strength to mass ratio d) All of the mentioned Question 3: Ceramics make excellent refractory materials. A material is said to be refractory if it: a) resists the flow of electric current b) has high refractive index c) retains its strength at high temperatures d) all of the mentioned Question 4: In terms of which of the following properties, metals are better than ceramics? a) Hardness b) Ductility c) Toughness d) Yield Strength Question 5: I general are heavy, good conductor, and can be shaped a) Metals b) Ceramics c) Polymers d) Composites

Answer 1

For polymer (a) They have very high molecular mass explanation: polymer are consist of large number of monomer. so, they have very high molecular mass. (b) They do not have linear stress strain curve. so, it is also true that they don't have linear stress strain behaviour (like Hookean region) (c) Polymers have very low density with compared to metals and ceramics. So, they have high strength to mass ratio. so, the answer is (d) All of the above. \r\n (c) A material is said to be refractory if it (c) Retain its strength at high temperature. Explanation For refractory material it is important to retain its strength at high temperature. Because it will be used at high temperature and if it looses its strength at that temperature it will break. This property is known as Refractoriness under load (RUL) (b) Metals are better than ceramics in terms of (b) Ductility. Explanation other properties like hardness, toughness, yield

Answer 2

Steels mainly contain iron and carbon. Under which of the following categories do they belong?