How many moles are there if the volume of a solution is 275 ml and molarity is 2.5M

If a polyatomic ionic compound has gained two hydrogen ions, then how does its name begin?

Ariver current has a velocity of 5km/h relative to the shore, and a boat moves in the same direction as the current at 5 km/h relative to the river. how can the velocity of the boat relative to the shore be calculated?

The molar mass of nickel(ni) is 58.7 g/mol. how many moles are in an 88 gram sample of nickel?