Question

Why acetamide and urea is weakly basic in aqeous solution but show acetic property in liquid ammonia

Answer 1

I am far from sure that the statement part of the question is correct or valid.

The only reference I have for “actinide” is that an actinide is a member of the transition group of elements, actinium to lawrencium (atomic numbers 89 to 103)

While their compounds may be acids or bases, the elements are neither. Nor do the elements form aqueous solutions.

I suggest that the OP has another look at the data and rewrites the question.