I NEED HELP :(
Which example is an exothermic reaction?

dissolving sugar in water

dissolving ammonium nitrate in water to cool the water

oxidation of iron

melting ice

An aqueous solution of potassium hydroxide is standardized by titration with a 0.194 m solution of hydrobromic acid. if 25.2 ml of base are required to neutralize 24.2 ml of the acid, what is the molarity of the potassium hydroxide solution? m potassium hydroxide

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

Sarah wants to know where in her garden chamomile would grow the best. she thinks chamomile will grow best in the corner of the garden that gets the most sunlight. to test her hypothesis, she decides to plant several groups of chamomile in her garden as an experiment. which of the following variables will sarah need to measure to know which group of plants grew best? a. the location of the plants b. the type of plants c. the height of the plants d. the amount of water she gives the plants