Sự xuất hiện của nhiều loại vũ khí (hình 31, 32) nói lên điều gì ?

Tính:  b )   6 11 x 7 12

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 46 to 55

Tsunami is a Japanese word which means harbour wave and is used as the scientific term for seismic sea wave generated by an undersea earthquake or possibly an undersea landslide or volcanic eruption. When the ocean floor is tilted or offset during an earthquake, a set of waves is created similar to the concentric waves generated by an object dropped into the water. Most tsunami originate along Ring of Fire, a zone of volcanoes and seismic activities, 32,500 km long that encircles the Pacific Ocean. Since 1819, about 40 tsunamis have struck the Hawaiian Islands.

A tsunami can have wave lengths, or widths, of 100 to 200 km, and may travel hundreds of kilometers across the deep ocean, reaching speech of about 725 to 800 kilometres an hour. Upon entering shallow coastal waters, the wave, which may have been only about half a metre high out at sea, suddenly grow s rapidly. When the wave reaches the shore, it may be 15m high or more. Tsunamis have tremendous energy because of the great volume of wave effected. They are capable of obliterating coastal settlements.

Tsunamis should not be confused with storm surges, which are domes of water that rise underneath hurricanes or cyclone and accompanying storm surge killed an estimated 500,000 people in Bangladesh in 1970. The tsunami which struck south and southeast Asia in late 2004 killed over 200 thousand people.

That is the greatest speed of tsunamis traveling across the deep ocean ?

A. 200 kilometres an hour

B. 700 kilometres an hour

C. 800 kilometres an hour

D. 150,000 kilometres an hour

Hỗn hợp X gồm axit HCOOH và CH₃COOH (tỉ lệ mol 1:1). Hỗn hợp Y gồm hai ancol CH₃OH và C₂H₅OH (tỉ lệ mol 3 : 2). Lấy 11,13 gam hỗn hợp X tác dụng với 7,52 gam hỗn hợp Y (có xúc tác H₂SO₄ đặc) thu được m gam hỗn hợp este (hiệu suất các phản ứng đều bằng 80%). Giá trị m là

A. 14,520

B. 15,246

C. 12,197

D. 11,616