Hi :) why must litmus paper be moistened to test for ammonia ?

Ammonia is gas.

Explanation:

If not moistened, there will be no change in color of litmus paper. That is why littmus paper is being moistened before testing the pH of a gas.

Hope it helps.

43.452

step-by-step explanation:

284 times .153 = 43.452

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.