SOME ONE HELLLPPP PLEASASE

Gymnast always perform on padded mats. how does the mats protect the gymnast

Cucl2 + 2nano3 cu(no3)2 + 2nacl what is the percent yield of nacl if 31.0 g of cucl2 reacts with excess nano3 to produce 21.2 g of nacl? 49.7% 58.4% 63.6% 78.7%

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