On which graph paper is absorbance plotted against concentration?

• A. Linear Graph Paper
• B. Semilogarithmic Paper
• C. Log-Log Paper
• D. Polar Coordinates Paper

Answer: (B)

Beer's law shows absorbance is directly proportional to concentration when path length and molar absorptivity are constant: A = εlc. Because of this direct relationship, plotting absorbance against concentration on ordinary linear graph paper yields a straight line with slope εl (and ideally through the origin). That straight-line behavior makes linear graph paper the natural choice for visualizing how absorbance changes with concentration and for determining concentration from measured absorbance. Using semilogarithmic paper would not produce a straight line here, since A depends linearly on c, not on its logarithm. The other graph types wouldn’t correctly reflect the direct proportionality described by Beer's law.