रसायन विज्ञान – Chemistry MCQ
रसायन विज्ञान – कृषि/वन प्रवेश
Chemistry · Agriculture, Veterinary & Forestry Entrance · ३९९ प्रश्न
३९९ 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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Sulphuric acid is manufactured on a large scale by the contact process, which involves oxidation of SO₂ to SO₃ with vanadium pentoxide catalyst.
सही उत्तर: क) burning sulfur directly
The contact process uses vanadium pentoxide as a catalyst to facilitate the conversion of sulfur dioxide (SO₂) to sulfur trioxide (SO₃), which is then used to produce concentrated sulfuric acid.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following best describes the role of oxidation states in predicting reaction stoichiometry?
सही उत्तर: ख) The sum of oxidation states for all atoms in a molecule or ion is equal to zero.
In redox reactions, the principle of conservation of mass requires that the sum of the oxidation states of all atoms must remain constant during the reaction (the total oxidation state is always 0). This concept allows for efficient stoichiometric calculations and balancing. Options 2 & 3 are partially correct but do not explain how oxidation states are used in balancing. Option 4 incorrectly asserts a lack of relevance.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What type of chemical reaction does the following process represent? The reaction of magnesium metal with hydrochloric acid to produce magnesium chloride and hydrogen gas.
सही उत्तर: ग) Redox (Reduction-Oxidation)
This is a neutralization reaction as an acid (HCl) reacts with a metal (Mg) to produce salt (MgCl₂) and a gas (H₂). Redox reactions involve changes in oxidation states. Precipitation involves the formation of solid compounds from solution. “
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction between iron(III) oxide (Fe₂O₃) and carbon monoxide (CO) produces iron(II) oxide (FeO) and carbon dioxide (CO₂). If 5 grams of Fe₂O₃ reacts completely with CO, what mass of CO₂ will be produced?
सही उत्तर: ग) 20 g
The balanced equation is: Fe₂O₃ + 3CO → 2FeO + 3CO₂. The molar mass of Fe₂O₃ is 159.69 g/mol and the molar mass of CO₂ is 44.01 g/mol. Therefore, 5 grams of Fe₂O₃ will produce (5/159.69) * 3 * 44.01 = 20g of CO₂. Option A incorrectly states the amount produced. Option B is too large and D is far too high.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the molar concentration (in mol/L) of a solution prepared by dissolving 4.4 grams of sodium chloride (NaCl) in 1 liter of water?
सही उत्तर: क) 0.25 M
Sodium chloride has a molar mass of 58.44 g/mol. To calculate the molar concentration (M), we divide the number of moles of NaCl by the volume in liters. (4.4 g / 58.44 g/mol) = 0.0746 mol. Therefore, the molar concentration is 0.0746 mol/L. Option B is incorrect because it overestimates the molar amount. Options C and D are incorrect as they are significantly higher than the calculated value.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In proteins, amino acids are covalently linked together via which type of bond?
सही उत्तर: ग) Peptide Bond
Amino acids are joined by a peptide bond formed through the condensation reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of another. This process releases water.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Rutherford's gold foil experiment, employing alpha particles, fundamentally revealed the existence of which subatomic particle?
सही उत्तर: ग) Neutron
The scattering pattern observed during Rutherford’s experiment demonstrated that atoms have a small, dense, positively charged nucleus. This discovery was pivotal in understanding atomic structure and directly supported the concept of the proton.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following processes utilizes calcium carbide (though now banned) for its intended purpose – achieving a chemical reaction that leads to fruit ripening?
सही उत्तर: ख) Hydrolysis
Calcium carbide reacts with water to produce acetylene. Acetylene then undergoes oxidation catalyzed by enzymes (produced by microorganisms) in the fruit, leading to ripening. The other options are irrelevant processes in this context.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Froth flotation is primarily utilized to concentrate which of the following materials from a slurry?
सही उत्तर: ख) Gold
Froth flotation is a technique used for separating minerals based on their surface properties. Specifically, it concentrates gold by selectively attaching air bubbles to gold particles, allowing them to float to the surface and be collected. The other options are not typically concentrated using this method.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The percentage yield of a reaction is calculated as:
सही उत्तर: ख) Theoretical Yield / Actual Yield
Percentage yield measures the efficiency of a chemical reaction by comparing the actual amount of product obtained to the theoretical maximum possible. The other options represent incorrect calculations or ratios.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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