I need help with both of these and the last question is true or false.

Express the following number in scientific notation. 0.026890 =

Which of the following statements about hybrid orbitals is or are true? choose all that apply. choose all that apply. under sp2 hybridization, the large lobes point to the vertices of an equilateral triangle. after an atom undergoes sp hybridization there is one unhybridized p orbital on the atom. the angle between the large lobes of sp3 hybrids is 109.5∘

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