Which of the following is a micronutrient for plants? MCQ with Answer and Explanation

Explanation:
The element with atomic number 13 is Aluminum. Its electronic configuration is 2, 8, 3. Since it has 3 electrons in its outermost shell, it loses these 3 electrons to achieve a stable octet configuration, making its valency 3. It forms Al³⁺ ions in chemical compounds.

Explanation:
Fermentation of sugar (glucose) by yeast produces ethanol and carbon dioxide—new substances are formed, so it's a chemical change. Melting, boiling are physical state changes. Magnetization aligns domains but does not change chemical composition. Chemical changes involve breaking and forming of bonds. Indicators: gas evolution, color change, heat, precipitate.

Explanation:
In the titration of a weak acid with a strong base, the equivalence point occurs in the basic region (pH > 7) due to the hydrolysis of the conjugate base formed. Phenolphthalein changes color in the pH range of 8.2 to 10.0, making it the most suitable indicator for detecting this basic equivalence point.