Joseph has found that when he passes a high voltage current through an evacuated tube, he can make a phosphor coating on one end of the tube glow. One day he makes the that if a metal shape is put in the middle of the tube, it casts a shadow on the phosphor coating.

The answer for #3 is c but i don't know why

Atrain travels 74 kilometers in 3 hours, and then 81 kilometers in 5 hours. what is its average speed?

Indicate whether the specified alkyl halides will form primarily substitution products, only elimination products, both substitution and elimination products, or no products when they react with sodium methoxide. 1-bromobutane 1-bromo-2-methylpropane 2-bromobutane 2-bromo-2-methylpropane