January 2018 Chemistry Regents #63-65

Highlight to reveal answers and explanations

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-54
 Questions 55-56 Questions 57-59 Questions 60-62 Questions 63-65  Questions 66  Questions 67-69  Questions 70-72 Questions 73-77 Questions 78-81 Questions 82-85  

 

 

 

 #63-65
  

The diagram below shows the first three steps in the uranium-238 radioactive decay series.

The decay mode for the first and third steps is shown above the arrows. The decay mode for the second step is not shown in the diagram. Thorium-234 has a half-life of 24.10 days.

63 Explain, in terms of neutrons and protons, why U-238 and U-234 are different isotopes of uranium. [1]

HIGHLIGHT TO SEE THE ANSWER

same number of protons but a different number of neutrons

64 Identify the decay mode particle emitted from the Th-234. [1]

HIGHLIGHT TO SEE THE ANSWER

beta

65 Determine the total time that must elapse until only 1/ 16 of an original sample of Th-234 remains unchanged. [1]

HIGHLIGHT TO SEE THE ANSWER

96.40 d....(4 half lives...4 x 24.10d)

 

  

on to Questions 66

  

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-54
 Questions 55-56 Questions 57-59 Questions 60-62 Questions 63-65  Questions 66  Questions 67-69  Questions 70-72 Questions 73-77 Questions 78-81 Questions 82-85