Passage IV
Atomic nuclei can be represented by the combination of symbols
where Z is the number of protons in a nucleus of Element X, and A (equal to Z plus the number of neutrons) is the mass number of the same nucleus. For example, 
represents a nucleus of carbon containing 6 protons and 6 neutrons;
represents a nucleus of a different isotope (type) of carbon that contains 6 protons and 8 neutrons.
Atomic nuclei undergo 3 types of radioactive decay. Particles emitted during the 3 types of decay are listed in Table 1. Figure 1 shows a sequence of radioactive decays, called the uranium series, that begins with the decay of 
.
18. Which of the following symbols correctly represents the isotope of radium (Ra) that is part of the radioactive decay sequence plotted in Figure 1 ?
Your Answer is
Correct Answer is J
Explanation
As can be seen from figure 1, the Z of the Ra element is 88, so 88 should be written in the lower left corner; the A of the Ra element is 226, so 226 should be written in the upper left corner