Chemical changes produce new substances. For this reason, they often cannot be undone. Some chemical changes can be reversed, sort of. To do so requires another chemical change to take place. For example, you can undo the tarnish on copper pennies by placing them in vinegar. The acid in the vinegar reacts with the tarnish. This is a chemical change that makes the pennies bright and shiny again. You can try this yourself at home to see how well it works. Other chemical changes cannot be reversed at all or may be difficult to do. Rusting is a chemical change. If metal rusts, the best you can do is to sand off the rust to get down to the shiny metal. Although the metal may now be shiny, the rust was removed. The rust was not changed back into the original metal. Some chemical reactions occur in only one direction. These reactions are called irreversible reactions. For example, you cannot change a fried egg back into a raw egg. Can you think of some other irreversible reactions related to cooking? Would you like a piece of cake?

Question: "What are some examples of irreversible reactions?"

Response: "rust"
OPTIONS:
- no
- yes

A: yes

Is this an insect or an animal? A snail is an animal just like you and me. Thats right, you too are an animal. No, you don't look like a snail. You do have some things in common. Animals can be divided into many groups. These groups are decided based on their characteristics. All animals have some basic features in common. That does not mean they are the same. They also have many differences. For example, snails are mollusks and not insects. Mollusks have a unique set of features. Notice the large foot that allows it to move. Yes, it only has one foot. Did you notice the long antennas on its head? This is where the snail's eyes are. They are on the end of the antenna. They are not on its head like most animals. The foot and eyes are unique features. Scientists use these features to place animals into groups.

Question: "Where are snails' eyes?"

Response: "On the face"
OPTIONS:
- no
- yes

A: no

Chinese Influences: The Japanese were forced out of the Korean peninsula in the sixth century, but not before the Koreans had bequeathed to the Yamato court copies of the sacred images and scriptures of Chinese Buddhism. Just as Christianity introduced Mediterranean culture into northern Europe, so Buddhism brought Chinese culture into Japanese society. Throughout the seventh and eighth centuries numerous Japanese monks, scholars, and artists made the perilous trip west across the Sea of Japan to study Chinese religion, history, music, literature, and paintinglater to be brought back for further development in Japan. An outstanding figure of this time was Prince Shotoku, who in 604 developed the "Seventeen-Article Constitution," outlining a code of human conduct and the ideals of state as a basic law for the nation. He also established relations with the Sui dynasty in China. Through him, the Japanese imperial court developed Chinese patterns of centralized government, with its formal bureaucracy of eight court ranks. The Chinese calendar was used to calculate the year of Japan's foundation by counting back the 1,260 years of the Chinese cosmological cycle. Thus, 660 b.c. is still the official date celebrated nationwide. At this early stage in its history Japan was already (for the most part) only nominally ruled by the emperor. De facto power was exercised by the militarily and economically strongest family. The Sogas had promoted Buddhism as an imperially sanctioned counterweight to the native Shinto religion, along with the new Chinese customs, to weaken the influence of their more conservative rivals. But they in turn were ousted in a.d. 645 by Nakatomi Kamatari, founder of the great Fujiwara clan, which was to rule Japanese affairs for hundreds of years and provide prominent advisers to the emperor even up to the 19th century.

Question: "Who was the economically strongest family in Japan's early history?"

Response: "The militarily strongest family"
OPTIONS:
- no
- yes

A:
yes