Question

The cell formed in bent pipes is an example of

• A. Concentration Cell
• B. Composition Cell
• C. Stress Cell
• D. Electrolytic Cell

Hint:

Remember that non-uniformity is a major cause of corrosion.
- Difference in metal type \(\rightarrow\) Galvanic/Composition Cell.
- Difference in oxygen concentration \(\rightarrow\) Differential Aeration Cell.
- Difference in mechanical stress \(\rightarrow\) Stress Cell.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The problem asks us to express the hardness caused by MgCl₂ as CaCO₃ equivalent in ppm.

Step 2: Key Formula or Approach:
Use the molar mass relationship to obtain the CaCO₃ equivalent and divide by the water mass to determine ppm.

Step 3: Detailed Explanation:
From 19 mg of MgCl₂, the CaCO₃ equivalent is \(19\times100/95=20\) mg. Since this quantity is present in 2 kg of water, the hardness becomes \(20/2=10\) mg/kg. Therefore, the hardness expressed in ppm is 10.

Step 4: Final Answer:
The degree of hardness is 10 ppm.