Please help me on these four question

Q4 : False

Q5: False

Explanation:

Those acts are morally praiseworthy that are done out of a sense of duty rather than for the consequences that are expected, particularly the consequences to self.  

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.