Question

Which of the following statements are correct about hard materials. a) They get scratched when rubbed against another b) Diamond and tooth enamel are the hardest substances known c) These substances cannot be compressed d) All the above​

Answer 1

Answer:

Hard: Material which are difficult to compress are called hard, e.g. diamond, stone, wood, steel, etc. Diamond is the hardest natural substance. Soft: Materials which can be compressed easily are called soft, e.g. chalk, cotton, rubber, etc.