Đốt cháy hoàn toàn x mol một peptit X mạch hở được tạo thành từ amino axit no Y chỉ chứa một nhóm – N H 2  và một nhóm –COOH thì thu được b mol C O 2  và c mol nước. Biết b – c = 3,5x. Số liên kết peptit trong X là

A. 6.

B. 8.

C. 10.

D. 9.

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

Any list of the greatest thinkers in history contains the name of the brilliant physicist Albert Einstein. His theories of relativity led to entirely new ways of thinking about time, space, matter, energy, and gravity. Einstein's work led to such scientific advances as the control of atomic energy, even television as a practical application of Einstein's work.

In 1902 Einstein became an examiner in the Swiss patent office at Bern. In 1905, at age 26, he published the first of five major research papers. The first one provided a theory explaining Brownian movement, the zig-zag motion of microscopic particles in suspension. The second paper laid the foundation for the photon, or quantum, theory of light. In it he proposed that light is composed of separate packets of energy, called quanta or photons, that have some of the properties of particles and some of the properties of waves. A third paper contained the "special theory of relativity" which showed that time and motion are relative to the observer, if the speed of light is constant and the natural laws are the same everywhere in the universe. The fourth paper was a mathematical addition to the special theory of relativity. Here Einstein presented his famous formula, E = m(cc), known as the energy mass equivalence. In 1916, Einstein published his general theory of relativity. In it he proposed that gravity is not a force, but a curve in the space-time continuum, created by the presence of mass.

Einstein spoke out frequently against nationalism, the exalting of one nation above all others. He opposed war and violence and supported Zionism, the movement to establish a Jewish homeland in Palestine. When the Nazis came to power in 1933, they denounced his ideas. He then moved to the United States. In 1939 Einstein learned that two German chemists had split the uranium atom. Einstein wrote to President Franklind. Roosevelt warning him that this scientific knowledge could lead to Germany developing an atomic bomb. He suggested the United States begin its own atomic bomb research.

According to the passage in which country did Einstein live in 1930s?

A. Switzerland

B. the United States

C. Germany

D. Israel