I think the secret lies with knowing the difference between a question and a statement. An example given above; Do you believe increase in salary leads to motivation of employees? This is a question and I believe that increase in salary leads to motivation of employees. This is a statement. Statements are more appropriate when they are responded to using the items such as Agree, Disagree and so on. Questions become more relevant when they are answered by yes or no together with a bit of elaboration.
An approach that bridges the two options you described is to start the set of items with a "stem question." In your example, it would be something like:
"For each of the following statements, to what extent do you believe that..."
1. Increase in salary leads to motivation of employees?
Although there is no any fixed rule for this, but most of Questionnaires contain Items in statement form. So I would recommend to follow statement approach.