What’s the mass number for this atom

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

The reactions of photosynthesis occur in the of plant cell? a.mitochondria. b. lysosomes. c. chloroplasts. d. chlorophyll

Mercury turns to vapor at 629.88 k how much heat is lost 175 g of mercury vapor at 650 current condenses to a liquid at 297 ca mercury turns to weber at 629.88 kelvin how much he is lost 175 g of mercury vapor and 650 coming condensers to liquidate 297 kevin