After chlorofluorocarbons we’re banned, which class of chemicals was used in their place

hydrofluorocarbons

methane

carbon dioxide

sulfur dioxide

Hydrofluorocarbons

Explanation:

Earlier chlorofluorocarbons were used for refrigeration purpose. But they were banned as they were primary cause of ozone depletion.

In order to replace  chlorofluorocarbons, now hydrofluorocarbons are used which helps to protect earth from stratospheric ozone-depleting substances.

The difference between chlorofluorocarbons and hydrofluorocarbons is of hydrogen. In hydrofluorocarbons one of the halogen is being replaced by hydrogen.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer