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Topic 3 - The Atomic Structure

8. Isotopes: Determining and recognizing symbols of isotopes

1. Which pair of atoms are isotopes?
14 14 40 40 222 232 40 42
3)
Rn 4) K and K
C and N
2) K and Ar
Ra and
1) 6 7 19 18 88 86 19 19
2. Which two atoms are isotopes?
24 24 21 23 3 3 7 9
1) Mg and Na 2) Na and Na 3) H and He 4) Li and Be
11 12 11 11 1 3 3 4

3. Which pair of atoms are isotopes of the same element X?

1) 226 X and X 2) 226 X and 227 X 3) 227 X and 227 X 4) 226 X and 227 X
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91 91 91 91 91 90 90 91

4. Which pair must represent isotopes of the same element?
14 14 12 6 2 4 12 13
2) X and X
4) X and X
3) X and X
X and X
1) 6 7 6 12 1 2 6 6
5. Which pair are isotopes?
1) Ba-56 and Mn-56 3) Ba-137 and Ba-139
2) Cs-137 and Ba-137 4) Cr- 52 and Mn-55

6. Which two symbols correctly show two isotopes of the same elements?
1) Iodine-53 and Xenon-54

3) Iodine-53 and Bromine-35

2) Iodine-127 and Iodine-128 4) Iodine-127 and Iodine-53

7. Which two nucleus symbols are from atoms of the same element?
10 p 11 p 18 p 18 p
20 n
22 n
11 n
1) 10 n 3)
10 p 11 p 18 p 20 p
2) 11 n 10 n 4) 20 n 10 n

8. Which atom is an isotope of Oxygen?
14 16 14 17
N 2 ) N 3) O 4) O
1) 7 8 7 8

9. Which symbol could be an isotope of calcium ?

40
40
1) 20 X 2) 20 X 3) X 4) X
20 40 20 40
19
10. Which name is correct for the isotope symbol represented as X ?
9

1) Potassium – 19 2) Potassium - 9 3) Fluorine – 19 4) Fluorine - 9
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11. If one isotope of an element has the symbol X . Which symbol could represent a different
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isotope of element X?
1) Rb - 88 2) Rb - 37 3) Rn – 86 4) In - 49
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