Answer:
the answer is b
Explanation:
convection is caused by density differences whereby warm air with less density rise above a heater and sink near a cold wind.
You need to find the abundance. Then, multiply the abundance by 100, and add that to the mass for each isotope. Basically, for each isotope, take the percentage abundance and add it to the mass. Multiply each calculation of these together to get your average atomic mass,
Here are 4 physical Properties of lanthanum
its
soft
malleable
ductile
and silver white colored metal.