Two assumptions of Law of the Diminishing Marginal Utility are:
(a) Every unit of a commodity must be same in-all respects-in size, color, quality, design etc. For example, if the quality of the second apple is superior to the first, the consumer may desire to mix utility from the second apple than from the first.
(b) The unit of the good must be standard, E.g. a cup of water, a bottle of cold drink, a pair of shoes, a full orange, a glass of lime juice. The units of the commodity should not be too small or too large. Otherwise, the law will not be applicable.
