If the SPF rating is 20 then it means it would provide 20 times the protection instead of no sunscreen and 20 times longer someone would take before the person started to burn or in this case 200 minutes.
Reaction of an alkene with H2 to form an alkane is an example of <u>reduction</u> reaction because there is an <u>increase</u> in the number of C-H bonds.
Yes baking soda is dissolved in vinegar and bubbles appear is a CHEMICAL CHANGE .
Combination or synthesis reaction
