Answer:
They assumed they both had water.
Explanation:
Because they only could look at it through telescopes that were not advanced
The simple trick which one can consider in such problem where it is asked for positron emission is :
<span>When the atomic number goes DOWN by one and mass number remains unchanged, then a positron is emitted.
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<span>a. </span>

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Here the atomic number decreases by one.
Similarly, options b and d are eliminated.
Option c is also not the answer.
For c, Count the atomic number on left side and compare it with right side. You will see it is 9 on left and 8 on right. Atomic no. did go down by 1. But the atomic mass is changed as well.
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Answer:
Uh, the second one?
Explanation:
Try to restate the question please.
The answer is GAS. Gas has a physical state characterized by having no definite volume or shape and consisting of neutral particles. or it can also be plasma.