For the isotope ${ }^{71} Ga , Z =$ $\qquad$ and $A =$ $\qquad$
A. 31; 40
B. $31 ; 69.723$
C. 71; 31
D. $71 ; 40$
E. 31; 71
Answer (1)
The isotope is given as 71 G a .
Identify the mass number A from the notation: A = 71 .
Recall that Gallium (Ga) has an atomic number Z = 31 .
Therefore, Z = 31 and A = 71 , so the answer is 31 ; 71 .
Explanation
Understanding the Notation We are given the isotope 71 G a and asked to find the values of Z and A . In the notation A X , A represents the mass number and X is the element symbol. The atomic number Z is the number of protons in the nucleus.
Identifying the Mass Number From the notation 71 G a , we can directly identify the mass number as A = 71 .
Finding the Atomic Number To find the atomic number Z , we need to know that Gallium (Ga) has an atomic number of 31. Therefore, Z = 31 .
Final Answer Thus, for the isotope 71 G a , we have Z = 31 and A = 71 .
Examples
Isotopes are used in various fields such as medicine, archaeology, and environmental science. For example, in medicine, radioactive isotopes like Gallium-67 ( 67 G a ) are used in imaging techniques to detect tumors and infections. The specific isotope 71 G a is not radioactive and has limited direct applications, but understanding its composition ( Z = 31 , A = 71 ) is fundamental to nuclear chemistry and physics. This knowledge helps in understanding the stability and properties of different isotopes, which is crucial for developing new medical treatments or industrial processes.
