Sample of radioactive element is it half-life of 3.0 days. It's 2.0 kg of the same several remains unchanged after 9.0 days, what was the initial mass of the sample question

What can you learn about precipitation levels in south america from this map? brazil is experiencing a drought.it rains more in higher altitudes.peru received the highest level of rain.venezuela got less than 25 cm of rain. 

Which of the following regions suffers the most from acid rain? a. the area around vancouver c. the area below atlanta b. the area below detroit d. the area above montreal

This country is the world's leading producer of cork?