David was working in his chemistry lab. He selected two isotopes, sample A and sample B. Sample A had longer half-life, but sample B had shorter half-life. After some time he checked sample A when its one half-life had passed. He noted it as sample A1. Then he came back to see it again when two half-lives had passed. He noted it as sample A2. Given the paragraph above, please answer correctly the following question: Would sample A have less or more isotopes than sample A1? Hint: Each radioactive isotope has a characteristic decay time periodthe half-lifethat is determined by the amount of time needed for half of a sample to decay. This is an exponential decay process that steadily decreases the proportion of the remaining isotope by 50% every half-life. Hence after two half-lives have passed only 25% of the isotope is present, and so forth.
Ans: more

John was reading about a fascinating story of a scientist in a science fiction book. In that novel the scientist met with a mysterious wormhole while visiting Antarctica. First, the wormhole started the time travel in present day, which was designated as point A. Then it sent the scientist to 170 million years in the past, which was designated as point B. The scientist had the rare experience of visiting Antarctica in two different time periods, 170 million years apart. Given the paragraph above, please answer correctly the following question: Would there be less or more life forms in point B than in point A? Hint: More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. Over time, Gondwana gradually broke apart, and Antarctica as we know it today was formed around 25 million years ago. Antarctica was not always cold, dry, and covered in ice sheets. At a number of points in its long history, it was farther north, experienced a tropical or temperate climate, was covered in forests, and inhabited by various ancient life forms.
Ans: more

Pat has 2 acres of land next to Tim's property. Tim's land is of similar size. The clay soil on Tim's property is very alkaline, so he had to amend it with aluminum salts to make it more acidic in order to grow crops. The soil on Pat's parcel has a good structure and high infiltration capacity. Pat gets twice as much food of his land every year. Given the paragraph above, please answer correctly the following question: Which farmer will get fewer crops this year? Hint: Alkali, or Alkaline, soils are clay soils with high pH (> 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell[1] and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils. Alkaline soils are basic, but not all basic soils are alkaline.
Ans: Tim

Two neighboring countries had health epidemics. While Ghana had a measles problem, Niger had a very serious HIV problem that seemed to get out of control. Given the paragraph above, please answer correctly the following question: Which country had more people at risk of getting AIDS? Hint: The Human Immunodeficiency Virus ( HIV ) is the virus that causes Acquired Immunodeficiency Syndrome ( AIDS ). Most researchers believe that the HIV originated in sub-Saharan Africa during the 20th century. HIV is transmitted by sexual contact and by contact with infected bodily fluids, such as blood, semen, breast milk, and vaginal secretions. It is also passed from mother to fetus. HIV is now a pandemic , with an estimated (as of 2008) 38.6 million people now living with the disease worldwide. It is estimated that AIDS has killed more than 25 million people since it was first recognized in 1981. For further information about HIV/AIDS, see the CDC (Centers for Disease Control and Prevention) web site at http://www.cdc.gov/hiv/resources/factsheets/ .
Ans: Niger