Which is true about UVA and UVB rays? A. Both rays can be blocked 100% by sunscreen
B. UVA protects the surface, UVB protects beneath the surface
C. UVB rays cause burning, UVA rays cause premature aging
D. UVA rays cause burning, UVB rays cause premature aging

I need help :

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?

Balloon a has charge q, and identical mass balloon b has charge 10q. you hang them from threads near each other. choose all of the statements with which you agree. check all that apply. a. a and b exert the same magnitude forces on each other. b. the force that a exerts on b is 10 times the force that b exerts on a. c. the angle between the thread supporting a and the vertical is < the angle between the thread supporting b and the vertical. d. the force that a exerts on b is 1/10 the force that b exerts on a.

The built in flash in a compact camera is usally capable of giving correct exsposure for distance up to how many meters?