PLEASE HELP THIS IS TIMED Which of the following is a physical change?
CsF(s) + XeFo(s) → CsXeF;(s)
CO2 (s) + CO2(g)
O N2 (g) + 3H2 (g) → 2NH3 (g)
2H2 (g) + O2 (g) → 2H20 (1)
Zn(s) + 2 MnO2(s) + H20(1) → Zn(OH)2(s) + Mn2O3(s)

Sodium nitrite (nano2) reacted with 2−iodooctane to give a mixture of two constitutionally isomeric compounds of molecular formula c8h17no2 in a combined yield of 88%. draw reasonable structures for these two isomers. click the "draw structure" button to launch the drawing utility. place the two compounds in the appropriate boxes below.

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.

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 : )