Alpha particles bouncing off of gold foil.
The answer is D, far apart and have weak attractive forces between them. The ideal gas means that the volume of molecule and the forces between them can be ignored.
My guess is b for the question
Ca=40.07841 ,Nitrogen=14.006722 ,Oxygen15.99943
molar mass= (1xMW of Ca)+(2xMWof N)+(6x MW of oxygen)
Molar mass (molecular weight) of Ca(NO3)2 is 164.0884 g/mol
