Subtract the mass number which is 157 from your atomic number which is 60. 157-60=97 neutrons.
<span>6.38x10^-2 moles
First, let's determine how many moles of gas particles are in the two-liter container. The molar volume for 1 mole at 25C and 1 atmosphere is 24.465 liters/mole. So
2 L / 24.465 L/mol = 0.081749438 mol
Now air doesn't just consist of nitrogen. It also has oxygen, carbon dioxide, argon, water vapor, etc. and the total number of moles includes all of those other gasses. So let's multiply by the percentage of nitrogen in the atmosphere which is 78%
0.081749438 mol * 0.78 = 0.063764562 mol.
Rounding to 3 significant figures gives 6.38x10^-2 moles</span>
When there are pi bonds as well as the sigma bonds, and therefore a double or triple bond. When it can change where that double bond is you can draw a resonance structure. Ozone, O3, has two resonance structures because you can rearrange the bonds in it.
Pretty sure the answer is c but not completely positive !
