The greatest loss of stratospheric ozone O is expected to occur in the mid-21st century
occurs in urban areas where automobilc use is most prevalent
has occurred over Antarctica
occurred after the Montreal Protocol failed to be ratified

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