Actually, I strongly believe it is a switch.
Explanation:
Mole = 0.5 = n/NA
n = no. of molecule
NA = avogadro number = 6.023x 10^23
so
N/NA = 0.5
N = 0.5 x 6.023 x 10^23
N = 3.0115 x 10^23
About 8.0 moles of methane.Number of moles = MassMolar mass.
And thus we get the quotient:
128.3⋅g16.04⋅g⋅mol−1=8.0⋅moles of methane.
Note that the expression is dimensionally consistent, we wanted an answer in moles, and the quotients gives, 1mol−1=11mol=mol as required.
Answer: Uranium-235.
Radioactive isotopes are used to determine the age of antique objects, including fossils.
The half-life time of the radioactive elements is what permits the process of dating.
The half-life of C-14 is too short to be useful to date too old objects.
Precambrian time is the most antique era. C-14 hal-life is about 5730 years and Precambrian time is millions or billions of years ago. Given that the hal-life of U-235 is 704 million years it is appropiate to date the fossils from the Precambrian era.
I believe the answer is C. (must be touching the object)
Someone please correct me if I am wrong.
