If a vertical line can intersect the graph of a relation more than once, the relation is not a function. (points : 5)
true
false

False.  That's called a "multivalued" function.

Examples:

         y = √(25 - x²)          (a circle,centered at the origin, with radius = 5)    
                 -5 < x < 5 

         y = √(kx)                 (a parabola, on its side, with vertex at the origin
                x >= 0               and axis along the x-axis)