Why is it important to keep high acid food away from zinc coated tub

The reactions that will take place will generate Zinc salts that will taint the food. Excessive levels of these salts can cause sickness, so it is very important to ensure food hygiene standards are met by keeping acidic foods away from damaging materials like zinc that will erode and get into the food.

Answer the air near the ground cools to its dew point

The answer would be solvent