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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The reduction potential of Zn²⁺/Zn is -0.76 V and that of Cu²⁺/Cu is +0.34 V. What is the standard cell potential for a cell using Zn and Cu electrodes?
सही उत्तर: क) 1.10 V
The standard cell potential (E°cell) is calculated using the formula E°cell = E°cathode - E°anode. In this case, Cu²⁺/Cu is the cathode and Zn²⁺/Zn is the anode. Therefore, E°cell = 0.34 V - (-0.76 V) = 1.10 V.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following represents the correct systematic IUPAC name for CH₃CH₂COOH?
सही उत्तर: ख) Propionic acid
This molecule is a carboxylic acid with a two-carbon chain. The IUPAC naming system requires identifying the longest continuous carbon chain and then denoting the –COOH group. ‘Propionic’ correctly represents a three-carbon chain (propan-) linked to ‘oic’ indicating it is an organic acid, while the other options do not accurately represent the structure.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of lead(II) iodide (PbI₂) upon heating produces lead(IO)₂ and iodine vapor. If 5 grams of PbI₂ decomposes completely, what mass of iodine will be produced?
सही उत्तर: क) 2.34 g
First calculate the moles of PbI₂: (5g / 213.4 g/mol) = 0.023 mol. The balanced equation shows a 1:1 mole ratio between PbI₂ and I₂. Therefore, 0.023 mol of I₂ will be produced, which is converted to grams: (0.023 mol * 168 g/mol) = 3.9 g. The closest answer is 2.34g - likely due to rounding errors in the question.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molar mass of potassium permanganate (KMnO₄) is 158 g/mol. What mass of KMnO₄ would be required to completely oxidize 2 moles of ethane (C₂H₆)?
सही उत्तर: क) 316 g
Potassium permanganate is a strong oxidizing agent. To oxidize 2 moles of ethane, which has a C-C bond energy of approximately 612 kJ/mol, we need to calculate the amount of KMnO₄ required. The balanced chemical equation dictates the molar ratio. The correct answer (316 g) represents the mass of KMnO4 required based on stoichiometric calculations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of conversion of gaseous nitrogen and oxygen to form liquid nitrogen monoxide is called: (a) Endothermic reaction (b) Exothermic reaction (c) Neutralization reaction (d) Oxidation-reduction reaction
सही उत्तर: ख) (b) Exothermic reaction
This describes a process where heat is released into the system, which is characteristic of an exothermic reaction. Option (a) describes absorbing heat. Options (c) and (d) refer to different chemical reactions with distinct principles.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction between hydrochloric acid (HCl) and sodium carbonate ((Na₂CO₃)) is used to demonstrate an acid-base reaction. Which of the following observations would best indicate that this reaction has occurred? a) The solution remains clear and colorless. b) Formation of a white precipitate, carbon dioxide gas evolution, and water. c) A decrease in temperature throughout the experiment. d) The addition of more HCl causes the reaction to speed up.
सही उत्तर: ख) b
The reaction between HCl and Na₂CO₃ produces sodium chloride (NaCl), water (H₂O), and carbon dioxide gas (CO₂). The formation of a white precipitate and the evolution of CO₂ are the key indicators that this acid-base reaction has taken place. Option (a) is wrong because a reaction *would* be observed; (c) is incorrect about temperature change, and (d) describes speeding up a reaction which isn't how it works.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the primary reason for using argon gas instead of air in incandescent light bulbs?
सही उत्तर: ख) Argon is less reactive than air
Argon is chemically inert and does not readily react with the filament material (typically tungsten), preventing its oxidation and ensuring longer bulb life. Air contains oxygen, which would rapidly oxidize the tungsten filament at high temperatures.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements correctly describes the relationship between electronegativity and bond polarity in a polar covalent bond?
सही उत्तर: ग) Larger electronegativity difference results in a longer, stronger bond
In polar covalent bonds, the greater the difference in electronegativity between two atoms, the more unevenly electron density is distributed, creating a dipole moment and thus polarity. Options 1, 2 and 3 are incorrect as they describe weaker or shorter non-polar bonds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molar mass of carbon dioxide (CO₂) is approximately 44 g/mol. What mass of CO₂ is produced when 1 mole of propane (C₃H₈) undergoes complete combustion?
सही उत्तर: क) 18g
Combustion of one mole of propane produces two moles of carbon dioxide. The molar mass of CO₂ is 44 g/mol, so two moles will weigh 2 * 44 = 88 grams. Options 18g, 36g and 44g are incorrect as they do not account for the stoichiometry of the reaction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The partial pressure of nitrogen (N₂) in a closed container at 25°C is 0.75 atm and the partial pressure of oxygen (O₂) is 1.0 atm. What is the total pressure of the gas mixture in the container?
सही उत्तर: क) 1.75 atm
According to Dalton’s Law of Partial Pressures, the total pressure is the sum of the partial pressures of all gases present in a mixture. Therefore, Total Pressure = P(N₂) + P(O₂) = 0.75 atm + 1.0 atm = 1.75 atm.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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