Assertion (A): Leguminous plants do not require nitrogenous fertilizers. Reason (R): They have Rhizobium bacteria in their root nodules that fix atmospheric nitrogen. MCQ with Answer and Explanation
Assertion (A): Leguminous plants do not require nitrogenous fertilizers. Reason (R): They have Rhizobium bacteria in their root nodules that fix atmospheric nitrogen.
A. Both A and R are true and R is the correct explanation of A.
B. A is true but R is false.
C. A is false but R is true.
D. Both A and R are true but R is NOT the correct explanation of A.
Answer: Option A
Solution (By JKSSB Mock Tests)
Leguminous plants (like peas, beans) have a symbiotic relationship with Rhizobium bacteria in their root nodules. These bacteria convert atmospheric N₂ into usable nitrogen compounds, fulfilling the plant's nitrogen needs. Thus, they generally do not need external nitrogenous fertilizers. Both statements are correct and R explains A.
Explanation:
Urea (CO(NH₂)₂) is a nitrogenous fertilizer with the highest nitrogen content (about 46%). Superphosphate provides phosphorus, muriate of potash (KCl) provides potassium, and gypsum (CaSO₄·2H₂O) is a soil conditioner providing calcium and sulfur, not primary NPK nutrients.
Explanation:
Normal rainwater is slightly acidic with a pH of about 5.6. This is due to the natural dissolution of carbon dioxide from the air into the rain droplets, forming weak carbonic acid (CO₂ + H₂O ⇌ H₂CO₃). Acid rain has a pH lower than 5.6 due to pollutants.
Explanation:
Tritium (³H) is a radioactive isotope with a half-life of ~12.3 years, decaying by beta emission to ³He. Protium (¹H) and deuterium (²H) are stable. Tritium is used in self-luminous paints, tracer studies, and nuclear fusion. It occurs naturally in very small amounts from cosmic rays but is mainly produced in nuclear reactors.
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