I) The Avogadro constant (N_A) is the number of constituent particles (atoms, molecules, ions, etc.) per mole of a substance. Its value is approximately 6.022 x 10²³ mol⁻¹.

b)

i) The Avogadro constant ($N_A$) is the number of constituent particles (atoms, molecules, ions, etc.) per mole of a substance. Its value is approximately $6.022 \times 10^{23} \text{ mol}^{-1}$.

ii) Step 1: Identify the given values and the formula.
Given:
Mass, $m = 0.217 \text{ g}$
Volume, $V = 47.1 \text{ cm}^3 = 0.0471 \text{ dm}^3$ (since $1 \text{ dm}^3 = 1000 \text{ cm}^3$)
Temperature, $T