Given the background: The earliest members of the human species evolved around 200,000 years ago in Africa. Early humans lived in small populations of nomadic hunters and gatherers. Human beings remained in Africa until about 40,000 years ago. After that, they spread throughout Europe, Asia, and Australia. By 10,000 years ago, the first human beings colonized the Americas. During this long period of time, the total number of human beings increased very slowly. Birth rates were fairly high but so were death rates, producing low rates of population growth. and the situation: Archaeologists studied data about human settlements. One was 100,000 years old called village R, and the other one was about 9,000 years old called village N. The older settlement was located in Africa, the other one wasn't. Answer the following question: Which village had more people that were gatherers?
Ans: village R

Given the background: Located mostly in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter. The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy fresh water inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years. and the situation: John sailed across two oceans last year. First, he sailed across the Atlantic Ocean, which he noted as location A. Then he sailed across the Arctic Ocean, which he noted as location B. He was so amazed by the Arctic Ocean that he sailed across that ocean twice, time C and time D. Time C was in the summer,and time D was in the winter. Answer the following question: Which would have less ice cover, time C or time D?
Ans: time C

Given the background: Many chemicals that were once commonly used were later found out to be harmful to the environment , to human health, or both. The element lead was once a common additive to gasoline and to paint. Plumbing pipes were once typically made of lead. Only since the 1970s has the danger of lead become apparent. It causes brain damage and small children (who often chewed on objects painted with lead-based paint) are particularly susceptible. The use of lead in gasoline, paint, and plumbing pipes is now banned and new materials are being developed to replace the hazardous lead components. and the situation: John is trying to buy a house. Today, he saw two houses, house A and house B. House A was build in the 1920s. It has lead plumbing pipes and lead based paint. House B was build recently. It does not have lead plumbing pipes or lead based paint. Answer the following question: Which house would be more dangerous for children, house A or house B?
Ans: house A

Given the background: As you can see in Figure above , solid and liquid solutes generally become more soluble as the temperature increases. This is true for solvents other than water as well. This effect varies quite a bit by substance. For example, the solubility of KNO 3 has a very strong temperature dependence (its solubility curve has a large slope), whereas the solubility of NaCl is minimally influenced by temperature (its solubility curve is nearly flat). For gaseous solutes, solubility decreases at higher temperatures. We will look more at this effect later in the lesson. and the situation: Keith was a studying for his chemistry exam. He got interested in solubility of different substances. For that, he conducted five tests, test A, test B, test C, test D, and test E. in test A, he used some liquid solute in a solvent in room temperature. Then in test B, he increased the temperature. In test C, he used some gaseous solute in a solvent in room temperature. But in test D, he increased the temperature. Finally, in test E he replaced the solvents in each of the earlier tests with water. Answer the following question: In which case the solute would be more soluble, case C or case D?
Ans: case C