The pH of human blood is approximately: MCQ with Answer and Explanation

Explanation:
Hardness is caused by Ca²⁺ and Mg²⁺ ions in the form of bicarbonates, sulfates, chlorides. They react with soap to form scum.

Explanation:
Sodium (alkali metal) reacts violently with cold water: 2Na + 2H₂O → 2NaOH + H₂ + heat. Copper and iron do not react with cold water; iron reacts with steam. Zinc also reacts with steam. Reactivity with water increases down Group 1.

Explanation:
NPK stands for Nitrogen (N), Phosphorus (P), and Potassium (K). These are the three primary macronutrients essential for plant growth. N promotes leafy growth, P aids root and flower development, and K improves overall health and disease resistance in crops.