Please help!! A balloon contains 7 L of He. The pressure is reduced to 2 atm and the
balloon expands to occupy a volume of 25 L. What was the initial pressure
exerted on the balloon? (round to the nearest whole number)

Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. in the first step, nitrogen and hydrogen react to form ammonia: (g) (g) (g) in the second step, ammonia and oxygen react to form nitric acid and water: (g) (g) (g) (g) calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. round your answer to the nearest .

Which organism develops breathing organism develops breathing organs from pharyngeal arches? shark, spider, sea star, sea horse

Condensation happens when water vapor cools. true or false? ?