Chapter 17 - Radioactivity and Nuclear Chemistry - Exercises - Problems - Page 637: 57

See the complete table below:

Let's check row by row. 1st Row: Chemical Symbol and Mass number are given in the 1st row. From, Chemical symbol we can find the no. of protons. See the periodic table. Tc has the atomic number 43. So, the no. of protons = 43 because atomic number is same as no. of protons. Now, we know that mass number = no. of protons + no. of neutrons. Here, Mass number = 95 and no. of protons = 43. So, no. of neutrons = 95-43 = 52. So, all blanks are filled in the 1st row. 2nd row: Here, Atomic number and mass number are given. From atomic number we can find the chemical symbol. See the periodic table. Barium (Ba) has the atomic number of 56. So, no. of protons = 56. Now, Mass number = 128. So, no. of neutrons = Mass number - no. of protons = 128-56 = 72. 3rd row: Here, Chemical symbol and no. of neutrons are given. From the chemical symbol we can find the atomic number of the element. See the periodic table. Atomic Number of Eu is 63. So, the no. of protons = 63. Mass number = No. of protons + No. of neutrons = 63 + 82 = 145. 4th row: Here, Chemical symbol and no. of neutrons are given. Atomic number of 'Fr' is 87 (see the periodic table). Hence, no. of protons = 87. And Mass number of the element = 87+136 = 223.