I need help! Not sure how to answer

Which formula can be used to calculate the molar mass of ammonia (nh3)? molar mass of n + molar mass of h 3 × molar mass of n + molar mass of h molar mass of n + 3 × molar mass of h 3 × molar mass of n + 3 × molar mass of h

Acamcorder has a power rating of 17 watts. if the output voltage from its battery is 7 volts, what current does it use?units:

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned