Answer:
It can be said to be reliable although it is not valid
Explanation:
This is because Reliability means an indicator of consistency, A measure should produce similar or the same results consistently if it measures the same quantity. So does the thermometer measures over 5days but it is not valid because it deviates from the real value
Any one trial might have been done incorrectly.
Yes, even light rays can vary in wavelength and frequency, if the length of the ray is sorter, it becomes more energetic and has a higher frequency. If you're talking about a ray tracing diagram for lenses or mirrors, the length of the ray doesn't really matter unless you're finding the path length but there are some procedures for that too. Let me know if I missed what you were asking.
A beta particle followed by another beta particle. Consider it beta positive decay in which a proton decays to form a neutron,positron and electron neutrino.
The equator - hope I helped you :)