Answer:
the answer for this question is the option D
The uranium within these items is radioactive and should be treated with care. Uranium's most stable isotope, uranium-238, has a half-life of about 4,468,000,000 years. It decays into thorium-234 through alpha decay or decays through spontaneous fission.
Answer:
3. The temperatures of the two substances equalize.
Explanation:
- As two objects at different temperatures are placed in contact, heat is transferred from the warmer to the cooler object until the temperature of the two objects be the same.
- The amount of heat that is transferred from the warmer object is equal to the amount of heat that is transferred into the cooler object.
- This is in agreement with the law of conservation of energy.
- <em>So, the right choice is: 3. The temperatures of the two substances equalize. </em>
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Some examples of physical changes are:
Breaking a glass
Chopping wood
Tearing paper
Mixing sand and water
Melting an ice cube
These all are physical changes because the composition of the matter does not change.