Final answer:
The question lacks context and clarity, making it impossible to provide an accurate answer or determine which subject or grade level it is associated with.
Step-by-step explanation:
The question as presented does not provide sufficient context to determine what topic it pertains to, nor does it give enough information to provide a concise answer. The term 'nul' is not clearly defined in the context of the question, which makes it challenging to apply to a specific rule or concept. If this question is related to significant figures, nul may refer to a null value or zero, which would indicate that leading zeros are not significant according to significant figures rules. However, without a clear numerical or situational context, it is not possible to specify which subject or grade level the question belongs to, nor accurately apply the given rules or answer the pondered questions related to reality, hypotheses, or motion and displacement.