How many moles are in 15.3 grams of KNO3?

0.151 mol

Explanation:

molar mass of KNO3 = (39.1 + 14 + 3×16) g/mol = 101.1 g/mol

number of moles = mass/molar mass

n = m/M = 15.3 g/(101.1 g/mol) = 0.151 mol

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.