Which of the following statements about the nucleus of an atom is FALSE:

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9

4 4

35

5

1. The nucleus has an overall positive charge.

2. The nucleus takes up a very small amount of space compared to the entire atom.

3. The nucleus contains both proton and neutrons.

4. The nucleus repels the electrons that orbit around it.

5. The nucleus contains most of the mass of the atom.

Countdown

60

Which of the following processes CANNOT transform one element into a different element (i.e. transmutation)?

1 2 3 4

3

19

2

331. Alpha decay2. Gamma decay3. Beta decay4. None of the above

Countdown

60

You have two atoms, one has 6 protons, 6 neutrons, and 6 electrons, and the other has 6 protons, 8 neutrons and 6 electrons. Which of the following best describes the difference between them?

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6

46

023

1. They are two different elements.

2. They are two different isotopes of the same element.

3. They are two different ions of the same element.

4. They are different ions of the same element.

5. None of the above.

Countdown

60

You have two atoms, one has 6 protons, 6 neutrons, and 5 electrons, and the other has 6 protons, 8 neutrons and 7 electrons. Which of the following best describes the difference between them?

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118

6

0

32

1. They are two different elements.

2. They are two different isotopes of the same element.

3. They are two different ions of the same element.

4. They are different ions of the same element.

5. None of the above.

Countdown

60

Uranium and Thorium are the two radioactive elements discovered by Marie Curie. What is your opinion?

1 2

52

5

1. True2. False

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30

The X-rays were discovered by J. J. Thompson. Do you agree?

1 2

49

8

1. Yes2. No

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30

Let’s consider two radioactive sources. One decays at a rate of 18.5 billion atoms per second, and the other decays at a rate of 74 billion atoms per second. What are their activities in curies?

1 2 3 4

5 33

461. 2 C and 1/2 C,

respectively.2. 1/2 C and 2 C,

respectively.3. 2 C and 3 C,

respectively.4. None of the above.

Countdown

120

Suppose you have 10 grams of Barium-139 which has a half-life of 86 minutes. After 86 minutes, half of the atoms in the sample would have decayed into another element, Lanthanum-139 (stable isotope). How many grams of Ba-139 and La-139 are present in the sample after 172 minutes?

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0

42

3

1. 2.5 grams and 5 grams, respectively.

2. 5 grams and 5 grams, respectively.

3. 2.5 grams and 7.5 grams, respectively.

4. None of the above.

Countdown

180

Which type of radiation causes the most biological damage to humans after a short exposure?

1 2 3 4

21 22

43

1. Gamma rays2. Beta particles3. X-rays4. Alpha particles

Countdown

30