This one is beta decay (the -1 subscript tells us that)
A. electron. The nucleus has protons and neutrons, quark is the particle which forms protons and neutrons.
solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 
They all have the same number of electrons in the electron cloud.
Answer:
Velocity is vector quantity. So it needs <em>direction</em> in addoition to <em>speed</em>.
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion.
