Who discovered the nucleus of an atom? MCQ with Answer and Explanation

Explanation:
Bakelite is a thermosetting plastic, heat resistant and electrical insulator. Polythene and PVC are thermoplastics; they soften on heating. Teflon is non-stick.

Explanation:
Across a period, the number of electron shells remains the same, but the nuclear charge (protons) increases. The added electrons enter the same valence shell, so the effective nuclear attraction on the electrons increases, pulling them closer and shrinking the atomic radius. Down a group, radius increases due to addition of shells. Electron-electron repulsion alone does not account for the trend. Atomic mass generally increases across a period.

Explanation:
Charles' law: V ∝ T (Kelvin) at constant P and n. V/T = constant. This means if temperature is doubled (in Kelvin), volume doubles. Temperature must be in Kelvin (K = °C + 273). Graph of V vs T is a straight line passing through origin. This law is used in hot air balloons: heated air expands, decreasing density, providing lift. Combined with Boyle's law gives PV = nRT.