Identify Periodic Table

What’s the percent by mass of carbon in c10h14n2

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

8) a mixture of he, ne and ar has a pressure of 7.85 atm. if the ne has a mole fraction of 0.47 and 8) ar has a mole fraction of 0.23, what is the pressure of he? a) 4.2 atm b) 3.7 atm c) 5.5 atm d) 2.4 atm e) 1.8 atm