Question

QUESTION 18

In balancing the nuclear reaction ²³⁸U =²³⁴X + alpha particle, the identity of element X is ___________.

		cannot determine from the information provided
		thalium
		thorium
		uranium
		plutonium

QUESTION 19

The decay of a radionuclide with a half-life of 4.3×10⁵ years has a rate constant (in 1/years) equal to __________.

		6.2×105
		2.3×10-6
		5.9×10-8
		1.6×10-6
		2.8×103

QUESTION 20

Radium was used to make glow-in-the-dark watches before it dawned on people that it may not be a good idea to put a strong radiation source on the public’s wrists. Suppose that your father (or grandfather) bought one of this watches 40 years ago. How much (%) of the radium remains in the watch if the half-life is 1600 years.

		29.2%
		62.7%
		93.7%
		97.8%
		10.9%

QUESTION 21

Element “A” decays into element “B” by an alpha emission. Element “B” is stable. Suppose a pure sample of “A” is prepared and then allowed to decay for 100 days. After the time over, the ratio of “A” to “B” is exactly 2 : 5 . What is the half-life of element “A” in days?

QUESTION 22

How much energy (in J) is produced when 0.082 g of matter is converted to energy?

		7.4×1015
		2.5×104
		2.5×107
		7.4×1018
		7.4×1012

QUESTION 23

The half-life of cobalt-60 is 5.20 years. How many milligrams of a 2.00 mg sample remain after 6.55 years?

		1.163
		3.23×10-15
		1.588
		0.837
		4.779

QUESTION 24

Uranium-235 fissions into a variety of products depending on how a particular atom splits apart. Suppose a neutron collides with an atom of U-235. The reaction creates a strontium-90 atom, three neutrons, and an atom with an atomic mass of ______________. Enter an INTEGER below.

Answer 1