## iheartfood 3 years ago #1: Carbon has different isotopes. What is different between an atom of 12C and an atom of 13C? A. number of protons in the nucleus B. number of neutrons in the nucleus C. number of electrons in the atom D. number of protons and electrons in the atom **My answer: B (BTW, the 12 and 13 are exponents =D )

1. iheartfood

#2: An atom has 16 protons and 17 neutrons. Write the chemical symbol for the atom. Consult the periodic table. A. 32S B. 33S C. 32Cl D. 33Cl **My answer: B. 33S (BTW, the numbers in the answer choices are also exponents!)

2. iheartfood

#3: Nitrogen (N2) is made up of 99.632% 14N and 0.368% 15N. The atomic mass of 14N is 14.003 amu. The atomic mass of 15N is 15.000 amu. What is the average atomic mass of nitrogen? A. 1.40 amu B. 14.007 amu C. 15.00 amu D. 155.00 amu **My answer: B. 14.007 amu

3. iheartfood

#4: Zirconium (Zr) has an average atomic mass of 91.22 amu and is made up of the isotopes 90Zr, 91Zr, 92Zr, 94Zr, and 96Zr. The atom of which isotope has the greatest mass? A. 90Zr B. 92Zr C. 94Zr D. 96Zr **My answer: D. 96Zr (again, numbers in front of the symbol are exponents!!! including the answer choices!!)

4. iheartfood

#5: Iridium has two isotopes, 191Ir and 193Ir. If 193Ir is found in abundance of 62%, estimate which mass number the average atomic mass will be closest to. A. 191 B. 192 C. 193 D. 19.2 **My answer: B. 192 (again, see above parentheses from#4.) :D

5. iheartfood

#6: An atom contains 32 protons and has a mass number of approximately 72 amu. What is the chemical symbol for the atom? A. 72Ga B. 72Ge C. 72As D. 72Zn ***im not too sure on this one, but i think its A. 72Ga not too sure on this one tho :(

6. iheartfood

hiiii!! what do u think??? :D

7. aaronq

hey! #1-#4 are right. for #5, is D supposed to be 192.2? or 19.2? #6 atomic number = protons.. 32 protons = Germanium

8. iheartfood

yayy!! :) and D is 19.2 i got 192.24, so i rounded to 192.. is that right?? and so #6 is B???

9. aaronq

yep! i was just asking because if it was 192.2, that would've been correct. but no it's 192, so you're right (Y) and 6 is B

10. iheartfood

woot woot!! =) thanks!! =)

11. aaronq

:) noo prob