2.50 × 10 ^-5. Move your decimal until you get a whole number. Then count how many times you moved it and that is your exponent. So your exponent is -5 because you're going to the left, if you're going to the right it would be a positive number.
They have a complete electronic configuration .their P shell is p6 therefore cannot gain or loose electron.
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Answer;
C) 228/90Th
Explanation;
-The above nuclear equation shows a beta radiation. The nuclide X undergoes beta radiation to form 228/89 Ac.
- When an unstable nuclide undergoes beta radiation the mass number remains the same while the atomic number is increased by one.
-Therefore, we can get the mass number and the atomic number of nuclide X, The mass number would be the same as 228 (its not affected by beta radiation) and the atomic number would be 89 (88+1).
The answer is "A" because Na = 22.9 and O =16 so it is 22.9*2+16
