What's a positive feedback loop

State the formula for density in words and mathematical symbols

Is this correct if not can u correct me

Imagine a small synthetic vesicle made from pure phospholipids enclosing an interior lumen containing 1 mm glucose and 1 mm sodium chloride. if the vesicle is placed in pure water, which of the following happens faster? a. na+ diffuses out. b. cl– diffuses out. c. h2o diffuses in. d. glucose diffuses out. e. sodium chloride diffuses out.