How can I find the vertical velocity

How many dots must be added to the symbol to properly represent a standard nitrogen ion? a) 1 b) 3 c) 5 d) 8

The most important difference between a wedge and an inclined plane is a. their size b. their shape c. how they are used d. what they are made of

On a day when the barometer reads 75.23 cm, a reaction vessel holds 250 ml of ideal gas at 20 celsius. an oil manometer ( ρ= 810 kg/m^3) reads the pressure in the vessel to be 41 cm of oil and below atmospheric pressure. what volume will the gas occupy under s.t.p.?