किसी पदार्थ के प्रति इकाई आयतन के द्रव्यमान को उसका क्या कहा जाता है?

When a bottle of perfume is kept open in a corner of a room, its fragrance is soon felt in all parts of the room. This occurs due to which phenomenon?

The quantity of matter contained in a substance is termed as:

What is the ability of a material, particularly a metal, to resist surface wear, scratching, and abrasion called?