रसायन विज्ञान – Chemistry MCQ
रसायन विज्ञान – कृषि/वन प्रवेश
Chemistry · Agriculture, Veterinary & Forestry Entrance · ३९७ प्रश्न
३९७ प्रश्न उपलब्ध। मोड छान्नुहोस्:
रसायन विज्ञान: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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Which of the following compounds is primarily used as a refrigerant?
सही उत्तर: घ) Carbon Dioxide
Carbon dioxide (CO₂) is widely used as a refrigerant due to its properties. Methane and butane are gases, and ammonia has specific industrial applications but isn’t commonly used for refrigeration.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of rusting of iron is primarily influenced by which chemical element present in the air?
सही उत्तर: क) Oxygen
Rusting of iron involves oxidation, and oxygen is the most common oxidizing agent. Carbon dioxide doesn't directly cause corrosion, nitrogen is not a primary reactant, and hydrogen plays no significant role in this process.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A solution has a chloride concentration of 0.05 M. What is the molarity of this solution?
सही उत्तर: क) A. 0.05
The question refers to Chloride concentration, and the question asks about molarity. The definition of Molarity is moles per liter. We are given that the chloride concentration is 0.05M, which is already its molarity.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the approximate percentage of carbon present in magnesium carbonate (CaCO₃)?
सही उत्तर: घ) D. 80%
The chemical formula for magnesium carbonate is CaCO₃, which contains one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O). Since the molar mass of C is approximately 12, and the molar mass of Ca and O are around 40 and 16 respectively, the percentage of Carbon is roughly (1 x 12) / (40 + 16 + 16) * 100 = 72%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of nitrogenous compounds in soil is primarily facilitated by which group of microorganisms?
सही उत्तर: क) A. Bacteria that convert ammonia into nitrate
Nitrifation, a crucial process in soil nutrient cycling, relies heavily on specific types of bacteria (primarily *Nitrosomonas* species) which convert ammonia to nitrite then nitrate. Option B is incorrect as fungi are involved in decomposition but not specifically nitrogen fixation; option C involves algal photosynthesis and option D refers to protozoa's role in controlling bacterial populations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of adding a substance to a liquid to cause it to dissolve is called: (a) Evaporation (b) Condensation (c) Dissolution (d) Precipitation
सही उत्तर: ग) Dissolution
Dissolution refers directly to the process of a solute dissolving in a solvent, which is the core concept tested. Evaporation describes liquid turning into gas; condensation is the opposite and precipitation involves solid formation. This aligns with basic chemistry principles.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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High levels of nitrate in drinking water can cause ‘blue baby syndrome’, which is: (a) Excessive iron absorption (b) Methemoglobinemia (c) Cyanide poisoning (d) Lead toxicity
सही उत्तर: ख) (b) Methemoglobinemia
Methemoglobinemia (option b) is the correct answer. Nitrate in drinking water converts to nitrite which then reacts with hemoglobin to form methemoglobin, reducing the oxygen-carrying capacity of blood. The tempting option ‘excessive iron absorption’ is incorrect as it relates to hemosiderosis and does not explain the blue discoloration.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following is a characteristic property used to distinguish between aldehydes and ketones?
सही उत्तर: घ) Only ketones undergo addition reactions
The Tollens' reagent (ammoniacal silver nitrate) specifically tests for aldehydes. Aldehydes reduce the silver ions to metallic silver, forming a characteristic silver mirror. Ketones do not exhibit this reaction. This question tests knowledge of specific chemical tests and functional group properties.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of potassium nitrate (KNO₃) upon heating produces nitrogen gas (N₂), oxygen gas (O₂) and potassium nitrite (KNNO₃). Which of the following is the correct balanced chemical equation for this reaction?
सही उत्तर: ग) 2 KNO₃ → 2 KNO₂ + N₂ + O₂
This equation balances the number of atoms of each element on both sides. It’s a classic decomposition reaction demonstrating gas evolution. The other options are unbalanced and show incorrect products. This question tests balance chemical equations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The mass percentage of carbon in C₆H₁₂O₆ (glucose) is calculated to be 40%. What is the mass of carbon in 100g of glucose?
सही उत्तर: क) 3.6g
The formula for calculating percentage composition is (mass of element / molar mass of compound) * 100. In this case, the mass of carbon is (40/180)*100=22.2%, which matches none of the options. The correct answer should be calculated based on the given percentages. This question tests understanding of percentage composition and calculation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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