1 = 90
2 = 65
3 = 65
4 = 25
90+25=115
180-115=65
have a merry christmas :)
General term of a geometric sequence is
a(n)=a(1)×r^(n-1)
a1=5
a2=5×6=30
a3=5×6²=180
a4=5×6³=1080
Answer:
The correct option is C: the isotope of iodine contains 81 neutrons.
Step-by-step explanation:
The mass (A) of the iodine isotope is given by:

Where:
Z: is the number of protons
N: is the number of neutrons
For iodine Z= 53, so if A = 134 the number of neutrons is:

Therefore, the correct option is C. The isotope of iodine contains 81 neutrons.
I hope it helps you!
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