Glass is considered a: MCQ with Answer and Explanation

Explanation:
All matter is composed of tiny particles (atoms, molecules, or ions). This is a fundamental concept. Matter may not always be visible (e.g., air). It can change states (solid, liquid, gas). Gases have mass; for example, a filled gas cylinder weighs more than an empty one. The particulate nature of matter explains diffusion, Brownian motion, etc.

Explanation:
Diamond has a three-dimensional network of strong covalent bonds between carbon atoms (sp³ hybridization). This giant covalent structure gives diamond its extreme hardness, high melting point, and electrical insulating property. Graphite also has covalent bonds within layers but conducts due to delocalized electrons. Ionic bonds are in NaCl, metallic bonds in metals, hydrogen bonds in water.

Explanation:
15/5 = 3 half-lives. Remaining = (1/2)³ = 1/8 = 12.5%. Each half-life reduces the amount by half.