If a sample of 2.00 moles of NO gas was reacted with excess
oxygen, how many moles of nitrogen dioxide gas would be
produced?

2 moles

Step-by-step explanation:

first you have to balance the equation:

2NO + O2⇒2NO2

then set up your mole to mole ratio

2 mol NO2/2 mol NO

multiply by the given 2.00 mol NO gas

and you should get 2 mol NO2

"?" = 3

Step-by-step explanation:

The answer can be gotten by subtracting 4 from 7. The 4 is the exponent in (4a^4b), and the 7 is the exponent in 16a^7b. So:

7 - 4 = 3

Therefore, the "?" = 3

Hope this helps :)