Ques: Q: The existence of what tiny, fundamental particles of matter was first proposed in the 1960s? Read this paragraph and choose the correct option from the provided answers: The existence of quarks was first proposed in the 1960s. Since then, scientists have done experiments to show that quarks really do exist. In fact, they have identified six different types of quarks. However, much remains to be learned about these tiny, fundamental particles of matter. They are very difficult and expensive to study. If you want to learn more about them, including how they are studied, the URL below is a good place to start. Choices: - atoms - molecules - neutrons - quarks A:
Ans: quarks

Ques: Q: Which theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as hexagonal rings of sp2-hybridized carbon atoms with the unhybridized p orbital of each carbon atom perpendicular to the plane of the ring? Read this paragraph and choose the correct option from the provided answers: Valence bond theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as hexagonal rings of sp2-hybridized carbon atoms with the unhybridized p orbital of each carbon atom perpendicular to the plane of the ring. Three valence electrons in the sp2 hybrid orbitals of each carbon atom and the valence electron of each hydrogen atom form the framework of bonds in the benzene molecule. The fourth valence electron of each carbon atom is shared with an adjacent carbon atom in their unhybridized p orbitals to yield the bonds. Benzene does not, however, exhibit the characteristics typical of an alkene. Each of the six bonds between its carbon atoms is equivalent and exhibits properties that are intermediate between those of a CC single bond and a C = C double bond. To represent this unique bonding, structural formulas for benzene and its derivatives are typically drawn with single bonds between the carbon atoms and a circle within the ring as shown in Figure 20.11. Choices: - hybrid orbital theory - covalent bond theory - molecular orbital theory - valence bond theory A:
Ans: valence bond theory

Ques: Q: The fetus becoming relatively large and mature before birth increases the chances of what? Read this paragraph and choose the correct option from the provided answers: The placenta permits a long period of fetal growth. As a result, the fetus can become relatively large and mature before birth. This increases its chances of survival. On the other hand, supporting a growing fetus may be difficult for the mother. She has to eat more while pregnant and may become less mobile as the fetus grows larger. Giving birth to a large infant is also risky. Choices: - disease - mutations - intelligence - survival A:
Ans: survival

Ques: Q: Oxygen, carbon, hydrogen and what other element make up approximately 96% of living matter? Read this paragraph and choose the correct option from the provided answers: Choices: - calcium - helium - silicon - nitrogen A:
Ans:
nitrogen