Ethanol is used as a fuel additive. The complete combustion of ethanol yields:
A. CO₂ and H₂
B. CO and H₂
C. CO₂ and H₂O
D. CO and H₂O
Answer: Option C
Solution (By JKExamLibrary)
Complete combustion of ethanol: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat. In sufficient oxygen, carbon burns to CO₂, hydrogen to H₂O. Incomplete combustion (lack of O₂) produces CO and soot (C). Ethanol is a biofuel, reducing CO₂ emissions if derived from biomass. It has high octane number and is blended with petrol (gasohol). CO₂ is a greenhouse gas, but bioethanol is carbon-neutral over cycle.
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 but R is NOT the correct explanation of A.
B.A is false but R is true.
C.A is true but R is false.
D.Both A and R are true and R is the correct explanation of A.
Explanation:
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:
Aqua regia (royal water) is a 3:1 mixture by volume of concentrated HCl and HNO₃. It generates nascent chlorine and nitrosyl chloride, which oxidize gold and platinum to soluble chloro complexes (e.g., HAuCl₄). Neither acid alone can dissolve these noble metals. Used for cleaning glassware and in etching. Must be prepared fresh and handled with extreme care.
Explanation:
Baking soda is sodium bicarbonate, with the chemical formula NaHCO₃. Sodium carbonate is washing soda (Na₂CO₃). Sodium hydroxide is caustic soda (NaOH), and calcium carbonate is limestone or marble (CaCO₃). Baking soda is widely used in baking as a leavening agent.
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