The Montreal Protocol limited the world’s use of chemicals like Chlorofluorocarbons (CFCs). Which sentence best indicates that the Montreal Protocol led to improvements in the thickness of the ozone layer? When ozone was first measured by satellite in 1979, the average concentration above Antarctica was 225 Dobson units (DU). In 1989, when the Montreal Protocol took effect, it was 127 DU. The lowest level was 92 DU in 1994.By 2019, the value was back up to 167 DU. Excerpt courtesy of NASA

In the following redox reaction which is the oxidizing agent and which is the reducing agent? alcl3 + na nacl + al

Long term exposure to waves can cause sunburns and skin cancer. a) visible b) infrared c) gamma rays d) ultraviole

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. 8. when a 2.5 mol of sugar (c12h22o11) are added to a certain amount of water the boiling point is raised by 1 celsius degree. if 2.5 mol of aluminum nitrate is added to the same amount of water, by how much will the boiling point be changed? show all calculations leading to your answer or use 3 – 4 sentences to explain your answer. 9. if 5.40 kcal of heat is added to 1.00 kg of water at 100⁰c, how much steam at 100⁰c is produced? show all calculations leading to an answer. 10. the freezing of water at 0⁰c can be represented as follows: h2o (l) ↔ h2o(s) the density of liquid water is 1.00 g/cm3. the density of ice is 0.92 g/cm3. in 3 – 4 sentences explain why applying pressure causes ice to melt.