A flask with a tap has volume 200cm^3 When full of air, the flask has a mass of 30.98g
The flask is connected to a vacuum pump, the air is pumped out and then the tap is closed. The flask now has a mass if 30.72g

Calculate the mass of the air in the flask before connecting to the vacuum pump, in grams.

Which of these properties, used alone, would be least useful in identifying most minerals? a. color b. luster c. streak d. density

Long term exposure to waves can cause sunburns and skin cancer. a) visible b) infrared c) gamma rays d) ultraviole

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.