$(a)$ Where is the ozone layer found?
$(b)$ What is an ozone hole and how is it caused?
$(c)$ State the harmful effects of ozone depletion.

(N/A) The ozone layer is found in the stratosphere,which is the upper layer of the atmosphere.
$(b)$ An ozone hole refers to the significant thinning of the ozone layer in the stratosphere. It is primarily caused by the release of man-made chemicals,specifically chlorofluorocarbons $(CFCs)$,into the atmosphere. These $CFCs$ rise to the stratosphere,where they are broken down by ultraviolet radiation,releasing chlorine atoms that react with and destroy ozone $(O_3)$ molecules.
$(c)$ The harmful effects of ozone depletion include:
$1$. Increased penetration of harmful ultraviolet $(UV)$ radiation to the Earth's surface.
$2$. Higher incidence of skin cancer and cataracts in humans.
$3$. Damage to the immune system and disruption of various ecosystems,including the reduction of crop yields and harm to marine life.