रसायन विज्ञान – Chemistry MCQ
रसायन विज्ञान – कृषि/वन प्रवेश
Chemistry · Agriculture, Veterinary & Forestry Entrance · ३८६ प्रश्न
३८६ 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 is a reducing agent in the reaction between iron(III) oxide and hydrogen?
सही उत्तर: ख) Iron(III) Oxide
In this reaction (Fe₂O₃ + 3H₂ → 2Fe + 3H₂O), hydrogen acts as the reducing agent because it gains electrons and reduces iron(III) oxide. Oxygen is an oxidizing agent in this case.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction of sodium hydroxide (NaOH) with a carboxylic acid produces what product?
सही उत्तर: ग) Aldehyde
Sodium hydroxide is a strong base and will react with a carboxylic acid to form an ester, which is an aldehyde. Option 1 and 3 represent other products formed through reactions involving bases, while option 2 represents the ether product formed from alcohol reaction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following compounds exhibits the highest degree of polarity due to uneven electron distribution?
सही उत्तर: ग) HCl (Hydrogen Chloride)
Ammonia (NH₃) has a pyramidal structure with nitrogen having lone pairs that create a significant dipole moment due to the difference in electronegativity between Nitrogen and Hydrogen. Methane, ethane, and hydrogen chloride have symmetrical structures or are relatively non-polar.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What type of chemical bond holds the atoms together in a water molecule (H₂O)?
सही उत्तर: ख) Covalent Bond
In water, oxygen shares electrons with hydrogen atoms to form covalent bonds. Covalent bonds arise from the sharing of electrons. Ionic bonds involve transfer; metallic bonds are found in metals. Hydrogen bonds are a weaker intermolecular force.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of calcium carbonate (CaCO₃) produces carbon dioxide gas. What volume of CO₂ gas will be produced upon the complete decomposition of 10g of CaCO₃ at standard temperature and pressure?
सही उत्तर: ख) 4.48 L
The balanced equation is CaCO₃ → CaO + CO₂. Using stoichiometry, the molar volume of CO₂ produced will be 2.24L at STP as this is the standard molar volume for one mole of a gas. The other options are incorrect because they don't account for the correct stoichiometry and volumes associated with complete decomposition.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molar mass of sulfuric acid (H₂SO₄) is approximately 98 g/mol. What volume of dilute sulfuric acid would be required to completely neutralize 5g of sodium carbonate (Na₂CO₃)?
सही उत्तर: ख) 200 mL
The balanced reaction is H₂SO₄ + Na₂CO₃ → Na₂SO₄ + H₂O + CO₂. Using stoichiometry, we can calculate the volume of sulfuric acid needed. Option 1 (200mL) is the correct answer as it's calculated based on the molar ratios and the given masses. The other options are incorrect because they don’t account for the specific reaction and resulting volumes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of nitrogen fixation converts atmospheric nitrogen into:
सही उत्तर: ग) Ammonium ions (NH₄⁺).
Nitrogen fixation, primarily carried out by bacteria, transforms atmospheric nitrogen gas (N₂) into ammonium ions (NH₄⁺), which is a form usable by plants. This process is crucial for the availability of nitrogen in ecosystems.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of hydrolysis involves:
सही उत्तर: क) The breaking down of a molecule by adding water.
Hydrolysis literally means 'splitting by water'. This process breaks down complex molecules, like carbohydrates or proteins, into simpler units through the addition of a water molecule. The other options describe distinct chemical processes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the primary purpose of adding manganese to a steel alloy?
सही उत्तर: ग) To improve its tensile strength and resistance to corrosion.
Manganese is added to steel alloys to significantly improve their magnetic properties, making them suitable for applications like transformer cores where strong magnetic fields are needed. While it does contribute to strength, the primary benefit is its magnetic contribution.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Across a period from left to right in the periodic table, the atomic radius generally decreases due to increasing nuclear charge. Which of the following statements best describes this trend?
सही उत्तर: ग) C) Decreases sharply as electrons are added to higher energy levels
The correct answer is (C). As you move across a period, the number of protons increases, leading to a stronger positive charge attracting the electrons. This increased attraction pulls the electrons closer to the nucleus, causing a decrease in atomic radius. Option A is incorrect as linear increase does not reflect observed trends. Option B describes behavior down a group, not across a period. Option D is false; nuclear charge significantly impacts the radius.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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