Q1.
Analyse Table 4.1. Identify the objects that are lustrous in appearance and hard.
Answer
The lustrous and hard objects are the piece of copper, the piece of aluminium and the iron nail.
Lustrous + hard → copper, aluminium, iron → these are metals
Non-lustrous + not so hard → coal, sulfur, wood
Non-lustrous + not so hard → coal, sulfur, wood
The shine that copper, aluminium and iron show is given a special name — metallic lustre.
Why it happens: the surface of a metal reflects light evenly, so it gleams. Coal and sulfur scatter light in all directions, so they look dull however much you polish them.