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
One, because blue litmus paper turns red in acid. Hope this helps!
Elements present in group 18 are known as noble gases. The outermost shell of these elements are completely filled.
18 is the answer