Answer
$\left.\begin{array}{cccccccc}
after\ (years) & 0 & 25,000 & 50,000 & 75,000 & 100,000 & 125,000\\
& & & & & & \\
quantity= & 16g & 8g & 4g & 2g & 1g & 0.5g
\end{array}\right.$
Work Step by Step
The quantity halves every $25,000$ years as follows:
$\left[\begin{array}{lllllll}
after\ (years) & 0 & 25,000 & 50,000 & 75,000 & 100,000 & 125.000\\
& & & & & & \\
quantity= & 16g & 8g & 4g & 2g & 1g & 0.5g
\end{array}\right]$
