Hạt nhân C 27 60 o  có khối lượng là 59,919u. Biết khối lượng của proton là 1,0073u và khối lượng của notron là 1,0087u. Độ hụt khối của hạt nhân  C 27 60 o là

A. 0,565u

B. 0,536u

C. 3,154u

D. 3,637u

Trong các loại tia: Rơn-ghen, hồng ngoại, tử ngoại, đơn sắc màu lục; tia có tần số nhỏ nhất là

A. Tia tử ngoại.

B. Tia hồng ngoại.

C. Tia đơn sắc màu lục.

D. Tia Rơn-ghen.

Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each the numbered blanks.

Setting up and running a car company was an expensive business and required a lot of workers. A company that makes its money out of a smart app requires less capital, doesn't have to pay (25) _____ storage or transport in the way that car companies do and (26) _____ virtually no extra costs as the number of users increases. In the jargon of economics, the marginal costs per unit of output tend towards zero and the returns to scale are high. This explains why tech entrepreneurs can get very rich very young.

Technological change has always been (27) _____. There was a polarization of income and wealth in the first wave of industrialization at the beginning of the 19^th century, and this gave rise to political and institutional change over the 100 years between 1850 and 1950: the spread of democracy, the emergence of trade unions; progressive taxation and the development of social safety nets. These helped create bigger markets for the consumer goods that were spawned by the second Industrial Revolution: TVs, radios, vacuum cleaners and the like. (28) _____ over the past four decades a political model that both facilitated the spread of technology and provided some protection against its disruptive consequences has come under attack. Welfare states have become less generous, levels of long-term unemployment are much higher, taxation has become less progressive, and politics has increasingly been dominated by those with the deepest pockets (29) _____ can lobby the loudest.

Điền vào số (26)

A. gives      

B. involves 

C. incurs     

D. takes

Nêu định nghĩa và các tính chất của khối lượng.