Hey Janet, good to see you again. a) Step 1: Compare the given Relative Atomic Mass (RAM) to the masses of the isotopes. The RAM of Boron is 10.81. The isotopes are $^{10}\text{B}$ (mass 10) and $^{11}\text{B}$ (mass 11). Step 2: Determine which isotope's mass the RAM is closer to. 10.81 is closer to 11 than it is to 10. Step 3: Conclude which isotope is more abundant. Since the average atomic mass (10.81) is closer to 11, the isotope with mass 11 must be more abundant. The more abundant isotope is $\boxed{\text{}^{11}\text{B}}$. b) The relative atomic mass is a weighted average of the masses of all naturally occurring isotopes of an element. Since most elements exist as a mixture of two or more isotopes, each with a different mass number, the average mass will typically not be a whole number. Send me the next one 📸