【简答题】The number of protons in the nucleus of a tin atom is 50, while the number of neutrons in the nucleus is 68. The atomic number and the mass number of this isotope are( ) and ( ).
【简答题】S1:What was the number of person in liferafts?S2:The number of persons in liferafts was 25.Q:What is the topic?A. The number of liferafts launched. B. The number of persons in liferafts. C. The number...
【简答题】The number of protons in the nucleus is equal to the number of electrons outside the nucleus in an atom and is called the atomic number of the atom.
【单选题】关于角膜的描述错误的是:
B.
角膜有+43D的屈光力,相当于生活中的放大镜