Why are positrons dangerous though they themselves do not usually penetrate?

During chemistry class, carl performed several lab tests on two white solids. the results of three tests are seen in the data table. based on this data, carl has concluded that substance b must have bonds.

What is the ph of a 0.0010 m hno3? 1.0 3.0 4.0 5.0

How does blood clotting prevent the entry of pathogens through cuts and wounds? answer asap,, this is due tomorrow. will mark as brainliest or whatever you call it : )