Using a cup, carefully pour water into the river, allowing it to flow from one end to the other (if needed, prop one end of the pan on top of the textbook to give it slope). Observe what happens to the sand as the water flows down the river and write down your observations.

what are the choices?

ok whats the question if not i cannot you i need question and need a thing to answer

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally

i think tornado but not 100%