Which bacterium is used as a biofertilizer for fixing atmospheric nitrogen in non-leguminous crops?
A. Nitrosomonas
B. Nitrobacter
C. Rhizobium
D. Azotobacter
Answer: Option D
Solution (By JKExamLibrary)
Azotobacter is a free-living aerobic bacterium that fixes atmospheric nitrogen in the soil, making it available to non-leguminous crops. Rhizobium is symbiotic and specific to legumes. Nitrobacter and Nitrosomonas are involved in nitrification (converting ammonia to nitrites/nitrates), not nitrogen fixation.
Explanation:
Teflon (PTFE) is polymerized tetrafluoroethene, repeating unit –CF₂–CF₂–. Option A is PVC, C is polythene, D is polystyrene. Teflon is highly inert, used in non-stick cookware.
Explanation:
Oxidation is defined as loss of electrons, increase in oxidation number, or loss of hydrogen / gain of oxygen. Reduction is gain of electrons. Oxidation does not always require oxygen; for example, 2Na + Cl₂ → 2NaCl involves oxidation of Na without oxygen.
Explanation:
Ionization energy (IE) is the minimum energy needed to remove an electron from an isolated gaseous atom in its ground state to form a cation. A(g) → A⁺(g) + e⁻. Adding an electron is electron affinity. IE is an indicator of reactivity. Metals have low IE, non-metals high IE.
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