GUYS HELP PLZZZ The partial pressure of oxygen in the atmosphere is 21.23 kPa. Calculate the partial pressure in atm. Be sure your answer has the right number of significant digits.

Write two balanced equations 1. dissolving of solid sodium hydroxide in water 2. the reaction of sodium hydroxide solution with hydrochloric acid

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6. using 3 – 4 sentences explain (in your own words) why water expands when it freezes? 7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation.