रसायन विज्ञान (Chemistry) – Chemistry MCQ
रसायन विज्ञान (Chemistry) – CEE प्रवेश
Chemistry · Medical Entrance (CEE) – Physics, Chemistry, Biology & MAT · ४१० प्रश्न
४१० प्रश्न उपलब्ध। मोड छान्नुहोस्:
रसायन विज्ञान (Chemistry): 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 factors primarily influences the rate of a chemical reaction?
सही उत्तर: ख) Temperature
The temperature has a significant impact on the kinetic energy of molecules and thus, directly affects the frequency of collisions. Increasing the temperature increases the reaction rate. The other options are irrelevant to the kinetics of chemical reactions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements correctly describes the properties of strong acids?
सही उत्तर: ग) They completely dissociate into ions in water
Strong acids completely dissociate into ions when dissolved in water, producing a large concentration of H⁺ ions. This leads to a significant conductivity and a low pH value. The other options describe weak acids which do not fully dissociate.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The equilibrium constant K for the reaction: N₂O₄(g) ⇌ 2NO₂(g) is 10⁻³ at 300K. If the initial concentration of N₂O₄ is 0.5 M, what is the concentration of NO₂ at equilibrium?
सही उत्तर: ख) 0.45
According to Le Chatelier's principle, equilibrium shifts to relieve stress. In this case, the shift favors the forward reaction to consume N₂O₄ and increase NO₂ concentration. Using an ICE table (Initial, Change, Equilibrium) will give a final answer of 0.45.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following compounds is a strong acid?
सही उत्तर: ग) C. Hydrochloric Acid (HCl)
The correct answer is C. HCl is a strong acid due to its complete dissociation in water and produces a high concentration of hydrogen ions. Acetic acid, formic acid, and citric acid are all weak acids and only partially dissociate in water.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the primary function of a reducing agent in a chemical reaction?
सही उत्तर: ग) C. To increase the pH of the solution.
The correct answer is B. A reducing agent donates electrons to another substance (the oxidizing agent), thereby causing oxidation in that substance and reduction in itself. Option A describes an oxidizing agent; option C relates to pH changes; and option D refers to a catalyst.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction between sodium hydroxide (NaOH) and magnesium carbonate (MgCO₃) produces sodium carbonate (Na₂CO₃), water, and carbon dioxide. Which of the following represents the balanced chemical equation for this reaction?
सही उत्तर: ख) B. NaOH + MgCO₃ → NaHCO₃ + H₂O + CO₂
The correct answer is A. This equation correctly represents the stoichiometry of the reaction between sodium hydroxide and magnesium carbonate to produce the expected products. Options B incorrectly simplifies the equation; C overproduces sodium carbonate; and D has incorrect chemical formulas.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements best describes the process of oxidation in organic chemistry?
सही उत्तर: घ) D. Loss of electrons by an atom or molecule.
The correct answer is D. Oxidation in organic chemistry specifically refers to the loss of electrons – typically represented by the gain of oxygen or loss of hydrogen – resulting in an increase in the oxidation state of a carbon atom. Option A describes reduction; option B is incorrect because oxygen isn't gained, and option C incorrectly associates with reduction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The dissolution of ammonium chloride (NH₄Cl) in water results in a decrease in pH. What is the primary reason for this change?
सही उत्तर: ख) B. The hydrolysis of ammonium ions (NH₄⁺).
The correct answer is B. Ammonium chloride is a salt that undergoes hydrolysis in water, producing H⁺ ions and increasing the acidity of the solution, thus lowering the pH. Option A is incorrect because ammonia doesn't directly cause acidification; option C is entirely false as HCl does not form from this reaction, and option D describes ion concentration changes, but not the mechanism behind the pH decrease.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of potassium chlorate (KClO₃) can be represented by the following equation: 2KClO₃(s) → 2KCl(s) + 3O₂(g). If 10 grams of KClO₃ decomposes, approximately how many grams of oxygen gas will be produced? (a) 2.5 g (b) 5.0 g (c) 7.5 g (d) 10.0 g
सही उत्तर: ख) (b) 5.0 g
First, calculate the moles of KClO₃: (10g / 122.5 g/mol) = 0.0816 mol. According to the balanced equation, 2 moles of KClO₃ produce 3 moles of O₂. Therefore, 0.0816 mol KClO₃ produces (3/2) * 0.0816 = 0.1224 mol O₂. Convert this to grams: 0.1224 mol * 32 g/mol = 3.90 g, which is closest to 2.5g. This question tests the student’s ability to apply stoichiometry and use molar masses correctly.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following salts will produce the largest volume of gas upon dissolution in water at standard conditions? (a) NaCl (b) KCl (c) Na₂CO₃ (d) KBr
सही उत्तर: ग) (c) Na₂CO₃
The volume of gas produced upon dissolution of a salt depends on the number of moles of hydrogen or oxygen gas evolved. Sodium carbonate (Na₂CO₃) decomposes to produce one mole of CO₂ for every mole of Na₂CO₃ dissolved, leading to the largest volume of gas compared to the other salts which produce less gas.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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