Which of the following salts is the main cause of permanent hardness of water?

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Which of the following salts is the main cause of permanent hardness of water? Answer: Magnesium sulphate

Magnesium sulfate (MgSO4) is the main cause of permanent hardness of water.

Question context

This question is part of 🔬 General Science within the broader 🌐 Current Affairs & GK subject and appears in the SPSC – Sindh Public Service Commission preparation collection. Reviewing the answer together with nearby questions helps reinforce the underlying concept and identify how it may appear in competitive exams.