Question

question 7
1 pts
how many protons are in potassium - 39?
24
20
39
15
19
question 8
1 pts
which of the following symbols are correct for the following isotopes?
radon - 220, polonium - 210, gold - 197
220 86 rn, 210 84 po, 197 79 au
220 134 rn, 210 126 po, 197 118 au
220 86 rn, 210 84 po, 197 119 au
220 84 rn, 210 84 p, 197 79 au
210 84 po, 220 84 rn, 197 79 au

Explanation:

Step1: Recall atomic number of potassium

Potassium has an atomic number of 19. The number of protons is equal to the atomic number. So for potassium - 39, the number of protons is 19.

Step2: Recall isotope notation rules

Isotope notation is written as $^{A}_{Z}X$, where $A$ is the mass number and $Z$ is the atomic number and $X$ is the chemical symbol. Radon has an atomic number of 86, polonium has an atomic number of 84 and gold has an atomic number of 79. For Radon - 220, the correct notation is $^{220}_{86}Rn$, for Polonium - 210 is $^{210}_{84}Po$ and for Gold - 197 is $^{197}_{79}Au$.

Answer:

Question 7: 19
Question 8: $^{220}_{86}Rn$, $^{210}_{84}Po$, $^{197}_{79}Au$