92.22% of all the isotopes of an element have a mass of 27.87 amu, 4.69% have a mass of 29.06 amu, and 3.09% have a mass of 30.09 amu. What is the average mass of this element?

Balance this equation: n2 + h2 > nh3, write the following molar ratios: n2 / n2 / nh3 h2 /

Three alkali metals in group 1 are a. calcium, strontium, barium b. boron, aluminum, gallium c. sodium, potassium, rubidium d. fluorine, iodine, chlorine

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided