About how old are the oldest meteorites (rocks that fall to Earth from space)? a
ID: 1479434 • Letter: A
Question
About how old are the oldest meteorites (rocks that fall to Earth from space)?
a. 3.8 billion years.
b. 2.5 billion years.
c. 4.57 billion years.
d. 4.21 billion years.
Where do the gamma-rays come from in PET diagnosis?
Electron-positron annihilation after the decay of the radio-pharmaceutical.
From the decay of 99mMo in the pharmaceutical.
Electron-positron annihilation after the + decay of the radio-pharmaceutical.
From the decay of 99mTc in the pharmaceutical.
a.Electron-positron annihilation after the decay of the radio-pharmaceutical.
b.From the decay of 99mMo in the pharmaceutical.
c.Electron-positron annihilation after the + decay of the radio-pharmaceutical.
d.From the decay of 99mTc in the pharmaceutical.
Explanation / Answer
Answer 1) option c i.e 4.55 billion years
Answer 2) option c i. e Electron-positron annihilation after the + decay of the radio-pharmaceutical.