What mass of NaOH must be added to the solution to increase the concentration to 30.00% by mass?

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

  the mississippians were considered to be  horticulturalists, which means they were

Which scientists contributed to the determination of how cfcs in clouds in the upper atmosphere could destroy ozone molecules