The average atomic mass of boron is 10.81 amu. Based on the atomic mass of B-10 and the relative abundances of the boron isotopes, what is the atomic
mass of B-11?
Isotope
Atomic mass (amu)
Relative abundance (%)
B-10
10.013
19.9
B-11
80.1
O A. 12.434 amu
OB. 11.009 amu
O C. 11.801 amu
O D. 9.084 amu

The zinc within a copper-plated penny dissolves in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can reach the zinc). the reaction between the acid and the zinc 2h+(aq)+zn(s)→h2(g)+zn2+(aq) . when the zinc in a certain penny dissolves, the total volume of gas collected over water at 25 °c is 0.947 l at a total pressure of 743 mmhg . (vapor pressure of water is 23.78 mmhg at 25 °c .) what mass of hydrogen gas is collected? answer in appropriate significant figures