Step 1: Assign Variables
Let the amount invested in Gold be $G$ and Bonds be $B$.
Given: $B = 25\% \text{ of } G \implies B = \frac{G}{4} \text{ or } G = 4B$.
Let $B = x$, then $G = 4x$.
Let the amount in Stocks be $S$.
Total Investment: $S + B + G = 1,00,000 \implies S + x + 4x = 1,00,000 \implies S = 1,00,000 - 5x$.

Step 2: Set up the Returns Equation
Total Gain = $10\% \text{ of } S + 6\% \text{ of } B + 8\% \text{ of } G = 8,200$.
$0.10(1,00,000 - 5x) + 0.06(x) + 0.08(4x) = 8,200$.
$10,000 - 0.50x + 0.06x + 0.32x = 8,200$.

Step 3: Solve for $x$ and Bond Gain
$10,000 - 0.12x = 8,200$
$1,800 = 0.12x \implies x = \frac{1,800}{0.12} = 15,000$.
The amount invested in Bonds ($B$) is Rs 15,000.
Gain from Bonds $= 6\% \text{ of } 15,000 = 0.06 \times 15,000 = \mathbf{900}$.