1. A pollen sample weighs 12 grams and contains 1-5 × 109 pollen grains.Calculate the weight of one pollen grain in grams.Give your answer in scientific notation. 相关知识点: 试题来源: 解析 1. 12÷1.5*10^9=8*10^(-5) grams
Generally, they fall into two main groups: (1) those emitted directly from identifiable sources and (2) those produced in the air by interaction between two or more primary pollutants, or by reaction with normal atmospheric constituents, with or without photoactivation. Exclusive of pollen, fog,...