GATE 2021 MT – Question 64
Nickel oxidizes isothermally at 800 K for 400 s, gaining 2 mg/cm$^2$. Its weight gain after 1600 s is ______ mg/cm$^2$ (nearest integer). Assume gain proportional to the square root of time.
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Show answer and explanation
Correct answer: 4 to 4
Explanation
Weight gain is proportional to √t. Increasing time from 400 to 1600 s multiplies it by √4=2.
Therefore gain is 2×2=**4 mg/cm²**.