Dalton's atomic theory could NOT explain: MCQ with Answer and Explanation

Explanation:
Ionization energy generally increases across a period due to increasing nuclear charge. Neon (noble gas) has the highest ionization energy in period 2 because of its stable filled octet (2s²2p⁶). Removing an electron requires enormous energy. Fluorine is next highest. Lithium has lowest. Noble gases have very high IE values, making them inert.

Explanation:
Using Boyle's law: P₁V₁ = P₂V₂ => 2 atm × 5 L = 1 atm × V₂ => V₂ = 10 L. As pressure decreases, volume increases. The same mass of gas expands. This is a direct application of inverse proportionality. If temperature and amount of gas are constant, doubling pressure halves volume, etc.

Explanation:
Atomic number 17 is chlorine. Electronic configuration: 2,8,7. Period number = number of shells = 3. Group number = 10 + valence electrons (for p-block elements) = 10+7 = 17. Hence Group 17 (halogens), Period 3. Group 1 has 1 valence electron, Group 16 has 6, Group 18 has 8 (except He). Simple method: period = number of shells.