Suppose a piece of silver jewelry contains 6.35×1022 atoms of silver (Ag). How many moles of silver atoms are in the piece of jewelry? Express your answer numerically in moles.

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?

For each of the following compounds, decide whether the compound's solubility in aqueous solution changes with ph. if the solubility does change, pick the ph at which you'd expect the highest solubility. you'll find ksp data in the aleks data tab. compounds does solubility change with ph