$(a)$ Meaningful : The addition of two scalar quantities is meaningful only if they both represent the same physical quantity. 
$(b)$ Not Meaningful : The addition of a vector quantity with a scalar quantity is not meaningful.
$(c)$ Meaningful : A scalar can be multiplied with a vector. For example, force is multiplied with time to give impulse.
$(d)$ Meaningful : A scalar, irrespective of the physical quantity it represents, can be multiplied with another scalar having the same or different dimensions.
$(e)$ Meaningful : The addition of two vector quantities is meaningful only if they both represent the same physical quantity.
$(f)$ Meaningful : A component of a vector can be added to the same vector as they both have the same dimensions.