How many moles of oxygen are needed to react with 3.75 grams of ammonia(NH3)? 4 NH3 + 5 O2 → 4 NO + 6 H20

Which of these conditions most likely produces an unstable isotope?

Ascientist measures the speed of sound in a monatomic gas to be 449 m/s at 20∘c. what is the molar mass of this gas?

Mercury metal is poured into a graduated cylinder that holds exactly 22.5 ml the mercury used to fill the cylinder mass in 306.0 g from this information calculate the density of mercury