Answer:
Sulfuric Acid Droplets
Step-by-step explanation:
"Venusian clouds are thick and are composed mainly (75–96%) of sulfuric acid droplets. These clouds obscure the surface of Venus from optical imaging, and reflect about 75% of the sunlight that falls on them.
Carbon dioxide: 96.5 %
Sulfur dioxide: 150 ppm
Water vapor: 20 ppm
Carbon monoxide: 17 ppm" by the Wikipedia