Question

which of the following has highest mass 1) 1g of N 2) 0.5g if NH3 3) 10 ml of h2o at stp 4) 3.011 x 10²³ atom of oxygen

Answer 1

the answer is 4 :
1 mole of oxygen that is 16g of oxygen contains 6.022×10^23 atoms
therefore converting 3.011×10^23 back to moles by dividing with avogadros constant (6.022×10^23) gives you 0.5moles
now to find the mass simply multiply it with 16 (gram atomic mass)
= 0.5 × 16 = 8g.