Which of the following is the best definition of half-life for a radioactive substance?
2 answers:
This is an incomplete question, here is a complete question.
Which of the following is the best definition of half-life for a radioactive substance?
A. Half of the amount of time required for all of the radioactive atoms to decay.
B. The amount of time required for half of the radioactive atoms to decay.
C. The amount of time required for each radioactive atom to decay halfway.
D. All of the above.
Answer : The correct option is, (B) The amount of time required for half of the radioactive atoms to decay.
Explanation:
Half life : It is defined as the amount of time taken by a radioactive material to decay to half of its original value.
All radioactive decays follow first order kinetics.
The relation between the half-life and rate constant is:
The half-life of the radioactive isotope is remains the same that means a constant value and it is not affected by any external conditions.
Hence, the correct option is, (B)
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Answer: A. The compound CuCl is 500 times less soluble in sea water than it is in pure water.
pure water.
Explanation:
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.
This principle states that if there is any change in a equilibrium reaction, the equilibrium will shift in a direction so as to minimize the effect.
Thus when a common ion is introduced to an equilibrium reaction, the equilibrium will shift in a direction where the concentration of common ion is decreasing.
When common ion such as from NaCl in sea water is introduced to an equilibrium reaction, the equilibrium will shift in a direction where the concentration of common ion is decreasing i.e. in the left side and thus solubility of CuCl further decreases.