61.Which of the following types of woods is specially used as railway sleepers ?

62.Given below are two statements, labeled as Assertion (A) and Reason (R). In the context of the two statements, which of the following is correct ? 1. Assertion (A) : Safety fuses are made up of materials having high melting point. 2. Reason (R) : Safety fuses should be resistant to electric current.

63.Given below are two statements, labeled as Assertion (A) and Reason (R). In the context of the two statements, which of the following is correct ? 1. Assertion (A) : Oil froth floatation method is used in the extraction of metal from its ore. 2. Reason (R) : It is used mainly for sulphide ores where ore settles down.

64.Which of the following substances is a polymer of isoprene ?

65.Given below are two statements, labeled as Assertion (A) and Reason (R). In the context of the two statements, which of the following is correct ?Assertion (A) : Soap removes oil and dirt.Reason (R) : Soap increases the surface tension of water.