How many moles of arsenic are in 1.204 x 10^24 atoms of arsenic?

Ahot-air balloon is drifting straight downward with a constant speed of 2.40 m/s. when the balloon is 7.63 m above the ground, the balloonist decides to drop one of the ballast sandbags to the ground below. how much time elapses before the sandbag hits the ground?

Afrequency generator sends a 550 hz sound wave through both water and ice. what is the difference in wavelength between the wave produced in ice and the wave produced in water?

Aprotein molecule in an electrophoresis gel has a negative charge. the exact charge depends on the ph of the solution, but 30 excess electrons is typical. what is the magnitude of the electric force on a protein with this charge in a 1600n/c electric field? write in two significant numbers, and also in newton