Recently, there has been haze weather in the central and eastern regions of China. The main pollutant causing haze is PM2.5 PM2.5, which refers to suspended matter with a diameter less than or equal t

Recently, there has been haze weather in the central and eastern regions of China. The main pollutant causing haze is PM2.5 PM2.5, which refers to suspended matter with a diameter less than or equal to 2.5. B

Test analysis: Some estimates of different physical quantities need to rely on life experience, some need simple calculation, some need to convert units, and finally decide which one is the most practical. According to PM2.5, it refers to particles with a diameter less than or equal to 2.5 microns in the atmosphere.

So choose B.

Comments: In physics, the ability to estimate various physical quantities is one of the important abilities that we should strengthen our exercise. The improvement of this ability is also of great practical significance to our lives.