Is shredding paper a physical or chemical change? explain why?

Which statement best describes how atoms combine to form sodium chloride (nacl)? a. a positively charged sodium ion and a positively charged chlorine ion form an covalent bond. b. a positively charged sodium ion and a negatively charged chlorine ion form an covalent bond. c. a positively charged sodium ion and a positively charged chlorine ion form an ionic bond. d. a positively charged sodium ion and a negatively charged chlorine ion form an ionic bond.

For the reaction, 4 a(g) + 3 b(g) => 2 c(g), the following data were obtained at constant temperature. experiment initial[a],mol/l initial [b],mol/l initial rate, m/min 1 0.200 0.150 5.00 2 0.400 0.150 10.0 3 0.200 0.300 10.0 4 0.400 0.300 20.0 which of the following is the correct rate law for the reaction? 1. rate = k[a]2[b]2 2. rate = k[a][b] 3. rate = k[a]2[b] 4. rate = k[a][b]2

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