Is someone kind enough to answer these questions as soon as possible!

What are the first three quantum numbers for the electrons located in subshell 2s?

Precision can be defined as the o exact center of a data set. o reproducibility of a measured value. o correlation between two variables that are measured in a data set agreement between a measured value and an accepted value.

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