Answer - Ozone layer helps keep the harmful ultra violet rays hitting and keeping the atmospheric pressure in.
Reasoning - Without the ozone layer the whole planet would have a loss of water and especially people burning very easily from the sun. <span />
Hepta is seven and tetra is four, so option c is your answer
<span>this
could be a substitution reaction. as you will locate, between the
hydrogen's on the propane chain replaced into substituted for a Br from
Br2. that's particularly no longer a addition reaction! addition
reactions artwork once you have a AlkENE! by using fact that's an AlkANE
it would not have a double bond to act as a nucleophile to attack the
Br2 (which might act as a electrophile to boot reactions).</span>
