Anyone else used to eat paper when they was in 2nd grade

Atomic nuclei of almost all elements consist of

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?

Aswimming pool whose volume is 10 comma 000 gal contains water that is 0.01% chlorine. starting at tequals0, city water containing 0.003% chlorine is pumped into the pool at a rate of 5 gal/min. the pool water flows out at the same rate. what is the percentage of chlorine in the pool after 1 hour? when will the pool water be 0.006% chlorine?