Answer the following question given this paragraph: Soil erosion is a natural occurrence. However, human activities have greatly accelerated soil erosion. In some locations, soil may now be eroding about 10 times faster than its natural rate. Since Europeans settled in the United States, approximately one-third of the topsoil has eroded away. Q: Since europeans settled in the united states, about what percentage of topsoil has eroded away? Choices: - 42 percent - 10 percent - 25 percent - 33 percent A:
33 percent
(Question)
Answer the following question given this paragraph: Recall that a double bond consists of one sigma bond and one pi bond. In order for a double bond to be formed, each participating carbon atom must have at least one unhybridized p orbital. In a carbon-carbon double bond where both carbons are bonded to two additional atoms, each carbon is sp 2 hybridized. The double bond includes a sigma bond between a hybrid orbital from each carbon and a pi bond between the leftover p orbital from each carbon. The angles between any two bonds for an sp 2 hybridized carbon are approximately 120. Q: What kind of bond consists of one sigma bond and one pi bond? Choices: - beta bond - covalent bond - ionic bond - double bond A:
(Answer)
double bond
Ques: Answer the following question given this paragraph: A stroke occurs when a blood clot blocks blood flow to part of the brain. Brain cells die quickly when their oxygen supply is cut off. Therefore, a stroke may cause permanent loss of normal mental functions. Many stroke patients suffer some degree of paralysis, or loss of the ability to feel or move certain parts of the body. If medical treatment is given very soon after a stroke occurs, some of the damage may be reversed. Strokes occur mainly in older adults. Q: What medical emergency occurs when a blood clot blocks blood flow to part of the brain, causing death of brain cells? Choices: - cardiac arrest - epileptic seizure - heart murmur - stroke A:
Ans: stroke
(Q).
Answer the following question given this paragraph: The scientists used geologic dating techniques on seafloor rocks. They found that the youngest rocks on the seafloor were at the mid-ocean ridges. The rocks get older with distance from the ridge crest. The scientists were surprised to find that the oldest seafloor is less than 180 million years old. This may seem old, but the oldest continental crust is around 4 billion years old. Q: Scientists found that the youngest rocks on the seafloor were where? Choices: - trenches. - mid - ocean sediments - mid - ocean glaciers - mid-ocean ridges A:
(A).
mid-ocean ridges
Ques:Answer the following question given this paragraph: O 3(g) O(g) + O 2(g) The reactive oxygen atoms recombine with molecular oxygen to complete the ozone cycle. The presence of stratospheric ozone decreases the frequency of skin cancer and other damaging effects of ultraviolet radiation. It has been clearly demonstrated that chlorofluorocarbons, CFCs (known commercially as Freons), which were present as aerosol propellants in spray cans and as refrigerants, caused depletion of ozone in the stratosphere. This occurred because ultraviolet light also causes CFCs to decompose, producing atomic chlorine. The chlorine atoms react with ozone molecules, resulting in a net removal of O3 molecules from stratosphere. This process is explored in detail in our coverage of chemical kinetics. There is a worldwide effort to reduce the amount of CFCs used commercially, and the ozone hole is already beginning to decrease in size as atmospheric concentrations of atomic chlorine decrease. While ozone in the stratosphere helps protect us, ozone in the troposphere is a problem. This ozone is a toxic component of photochemical smog. The uses of ozone depend on its reactivity with other substances. It can be used as a bleaching agent for oils, waxes, fabrics, and starch: It oxidizes the colored compounds in these substances to colorless compounds. It is an alternative to chlorine as a disinfectant for water. Q: The presence of what stratospheric gas layer decreases the frequency of skin cancer and other damaging effects of ultraviolet radiation? Choices: - plasma - cumulonimbus - smog - ozone A:

Ans:ozone
Ques: Answer the following question given this paragraph: The dermis also contains hair follicles and two types of glands. You can see some of these structures in Figure below . Q: How many types of glands does the dermis contain? Choices: - three - ten - six - two A:
Ans:
two