Concept:For a fixed length of magnesium ribbon, the surface area remains constant, so the rate of gas evolution is directly proportional to the acid concentration.
Explanation:When the concentration of the acid increases, more acid particles are present per unit volume.
Therefore, more effective collisions occur with the magnesium surface in a given time.
This causes the rate of hydrogen gas evolution to increase uniformly.
Rate of H2 evolution∝[acid]A direct proportional relationship is shown by a straight line passing through the origin.
Among the given graphs, graph I is the one that shows this linear increase in rate as concentration rises.
Answer:Option A — I
