Final answer:
A morally wrong maxim that violates the 1st formulation of Kantianism is 'It is acceptable to lie whenever it benefits me personally.' This maxim is morally wrong because it cannot be universalized.
Step-by-step explanation:
A morally wrong maxim that violates the 1st formulation of Kantianism is 'It is acceptable to lie whenever it benefits me personally.' According to the first formulation of Kantianism, we should only act according to maxims that we can will to be universal laws. If everyone were to adopt the maxim of lying whenever it benefits them, trust and communication would break down, resulting in chaos and an inability to achieve our desired ends. Therefore, this maxim is morally wrong because it cannot be universalized.