Repeated measurement of Pb in a lake water sample gave 3.2, 5.2 and 7.2 ppb of Pb. Standard deviation in the measurement of Pb is

(a) 2 ppb. Explanation: Mean 5.2; s = √[(2² + 0 + 2²)/(3 − 1)] = 2 ppb (a).

Q21 · CSIR-NET Chemistry, December 2017

Paper: CSIR-NET December 2017 · Subject: Physical Chemistry · Chapter: Data Analysis · Topic: Error Propagation · Marks: 2 · Difficulty: Medium

Repeated measurement of $Pb$ in a lake water sample gave $3.2, 5.2$ and $7.2\,\mathrm{ppb}$ of $Pb$. Standard deviation in the measurement of $Pb$ is

(a)$2\,\mathrm{ppb}$

(b)$4\,\mathrm{ppb}$

(c)$0\,\mathrm{ppb}$

(d)$\sqrt{2}\,\mathrm{ppb}$

Answer

Answer: A ✓ checked by 4AB · confidence high

Explanation

Mean 5.2; s = √[(2² + 0 + 2²)/(3 − 1)] = 2 ppb (a).

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