Which of the following is a phosphate fertilizer? MCQ with Answer and Explanation

Explanation:
Oxidation is loss of electrons. Na loses an electron to become Na⁺, so it is oxidized. Options A, C, D involve gain of electrons (reduction). Oxidation also can be defined as gain of oxygen or loss of hydrogen. In the reaction, Na acts as reducing agent. Mnemonic: LEO (Loss of Electrons is Oxidation) GER (Gain of Electrons is Reduction).

Explanation:
Boiling converts soluble bicarbonates of Ca and Mg to insoluble carbonates: Ca(HCO₃)₂ (heat) → CaCO₃↓ + H₂O + CO₂, which can then be filtered. Permanent hardness (due to sulfates/chlorides) is not removed by boiling; requires washing soda, ion exchange, or calgon. Calcium sulfate addition would increase permanent hardness. Filtration removes solid particles, not dissolved ions.

Explanation:
Primary air pollutants are emitted directly from a source. Carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen oxides (NOx) are primary pollutants. Ozone, PAN, and sulfuric acid are secondary pollutants, formed in the atmosphere by reactions of primary pollutants.