Can endothermic chemical reactions be spontaneous?

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

What is the lowest number energy level where a d sublevel is found

What will most likely happen in the absence of a cell membrane? a) photosynthesis will not take place. b) the cell will not store food, water, nutrients, and waste. c) energy will not be released during cellular respiration. d) substances will pass in and out of the cell in an uncontrolled manner.