Chapter 17 - Radioactivity and Nuclear Chemistry - Exercises - Problems - Page 637: 58

See the complete table below:

Let's solve this problem row by row. 1st Row: Here, chemical symbol, Atomic Number and No. of neutrons are given. No. of protons will be equal to Atomic Number. Hence, Number of protons = 46. Mass number = no. of protons + no. of neutrons = 46+54 =100. 2nd Row: Here, Chemical symbol and Mass number are given. From Chemical symbol of the element we can find the atomic number. See the periodic table of elements. Atomic Number of Ce = 58. Hence, no. of protons = 58 and no. of neutrons = Mass number - no. of protons = 136-58 = 78. 3rd Row: here, Atomic number and Mass number are given. See the periodic table to find the chemical symbol from the atomic number. 84 is the atomic number for 'Po'. So, no. of protons = 84 (atomic number = no. of protons). No. of neutrons = Mass number - no. of protons = 208-84=124. 4th Row: Here, no. of protons and no. of neutrons are given. So, the atomic number will be equal to no. of protons i.e. 88. Chemical symbol of the element having atomic number is 'Ra'. Mass number of the element = 88+138= 226. (mass number = no. of protons + no. of neutrons)