June 2015 Chemistry Regents #62-65

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Question 62-65

 

 

Base your answers to questions 62 through 65 on the information below and on your knowledge of chemistry.

Some isotopes of potassium are K-37, K-39, K-40, K-41 and K-42. The Natural abundance and the atomic mass for the naturally occurring isotopes of potassium are shown in the table below.

62 Identify the decay mode of K-37 [1]

Answer--> Positron

B

+
 

0

B

+1

63 Complete the nuclear equation in your answer booklet for the decay of K-40 by writing a notation for the missing nuclide. [1]

Answer-->

40

Ca

20

64 Determine the fraction of an original sample of K-42 that remains unchanged after 24.72 hours. [1]

Answer--> 1/4

Use table N

Work not required    24.72h/12.36h= 2 half lives 

1--> 1/2--> 1/4

65Show the correct numerical setup for calculating the atomic mass of potassium. [1]

Answer-->

((93.26)(38.96))+((0.01)(39.96))+((6.73)(40.96))

100

or

((93.26)(0.3896))+((0.0001)(39.96))+((6.73)(0.4096))

on to Questions 66-68

 

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 51-53 Questions 54-56 Questions 57-59 Questions 60-61 Questions 62-65 Questions 66-68 Questions 69-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

 

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