What is the total number of molecules in 11.2 liters of n2 gas at stp

Molar volume at STP = 22,4 L

1 mole 22,4 L
 x mole 11,2 L

x = 11,2 / 22,4

x =  0,5 moles of N2

1 mole 6,02.10²³ molecules
0,5 moles y molecules

y = 0,5 . 6,02.10²³

y = 3,01.10²³ molecules 

Ibelieve it is b. proton.hope my answer has you : )

The phase where ice changes directly to gas is called sublimation