The correct statement is
Ultraviolet light has both a higher frequency and a higher radiant energy than visible light.
because ultraviolet light has wavelength smaller than the visible light hence has a greater frequency as compared to visible light. (frequency is inversely related to wavelength. hence smaller the wavelength , greater will be the frequency)
we also know that the radiant energy is directly proportional to the frequency. hence greater the frequency , greater will be the radiant energy.
Since the frequency is greater for ultraviolet light , it radiant energy is also greater
The object's speed will not change.
In fact, after the astronaut throws the object, no additional forces will act on it (since the object is in free space). According to Newton's second law:

where the first term is the resultant of the forces acting on the body, m is the mass of the object and a its acceleration, we see that if no forces act on the object, then the acceleration is zero. Therefore, the acceleration of the object is zero, and its velocity remains constant.
The units of velocity is :
meter per second (m/s)