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 percentage by mass of carbon in magnesium carbonate (MgCO₃) is approximately what?
सही उत्तर: ख) 40%
Magnesium carbonate’s formula is MgCO₃. Calculating the mass percentages reveals that carbon constitutes about 40% of the compound's mass. The other options are incorrect because they derive from calculating the actual percentages based on the chemical formula.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Given E°(Cu²⁺/Cu) = +0.34 V and E°(Zn²⁺/Zn) = −0.76 V, what is the standard cell potential (E°cell) for a Daniell cell?
सही उत्तर: ख) -1.1 V
The standard cell potential is calculated as E°cell = E°(cathode) - E°(anode). In this case, the cathode is Cu²⁺/Cu (+0.34 V) and the anode is Zn²⁺/Zn (-0.76 V). Therefore, E°cell = 0.34 - (-0.76) = 1.1 V.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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'Normal saline' administered intravenously is approximately isotonic with blood. What is the approximate molar concentration of NaCl solution typically used for normal saline?
सही उत्तर: ग) 3.0 M
Standard intravenous saline solutions are prepared at a 0.9% (w/v) concentration of NaCl, which is approximately equal to 0.9 M. This isotonicity helps maintain fluid balance in the bloodstream. Other concentrations would either be hypertonic or hypotonic, disrupting cellular function.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 25 mL solution of 0.1 M oxalic acid (H₂C₂O₄) is titrated with 0.02 M potassium permanganate (KMnO₄) in acidic medium. What volume of KMnO₄ is required for the complete neutralization?
सही उत्तर: ग) 10 ml
The balanced equation shows a 1:1 mole ratio between oxalic acid and permanganate. Using stoichiometry, the volume of KMnO₄ needed to react completely with 25 mL of 0.1 M H₂C₂O₄ is calculated as (25/100) * 0.02 = 0.05 L or 5 ml. The other options arise from incorrect application of stoichiometry.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What is the chemical formula for aspirin?
सही उत्तर: ख) CₙH₅COOH
Aspirin is chemically known as acetylsalicylic acid. This formula accurately represents the structure where salicylic acid has been reacted with acetic anhydride to form an ester bond. The other options represent incorrect chemical structures of related compounds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The van Arkel method utilizes a catalytic process to produce ultrapure iodine (I₂) from its corresponding compound. This process relies on the removal of hydrogen gas as a byproduct, driven by a chemical equilibrium shift. What is the primary chemical reaction involved in this purification?
सही उत्तर: क) I₂ + H₂ → 2HI + Energy
Option 0 is correct. The van Arkel method uses iodine chloride (ICl) and heat to decompose it into iodine and chlorine gas, shifting the equilibrium towards iodine production. Option 1 represents the formation of hydrogen iodide, which is not part of this process; option 2 describes a different reaction involving chlorine, and option 3 incorrectly suggests a simple thermal decomposition.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The term 'degree of unsaturation' represents: (a) The number of saturated carbon atoms in a molecule. (b) The number of double or triple bonds present in a molecule, plus ring structures. (c) The total mass of the molecule. (d) The temperature at which a substance boils.
सही उत्तर: ख) (b) The number of double or triple bonds present in a molecule, plus ring structures.
Option (b) is correct because the degree of unsaturation directly relates to the number of multiple bonds and rings within a molecule's structure, providing information about its reactivity.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of converting a primary alcohol into an ether using sulfuric acid is known as: (a) Reduction (b) Oxidation (c) Esterification (d) Dehydration
सही उत्तर: घ) (d) Dehydration
Option (d) is correct because dehydration of a primary alcohol with sulfuric acid results in the formation of an ether and water. Options (a), (b), and (c) represent different chemical processes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction between sodium metal and alcohol produces sodium alkoxides and hydrogen gas. Which of the following statements accurately describes this type of reaction? (a) It is an exothermic process that releases heat. (b) The rate of the reaction increases with increasing temperature. (c) It involves a change in oxidation state of sodium. (d) It is a displacement reaction where a more reactive metal replaces hydrogen.
सही उत्तर: क) (a) It is an exothermic process that releases heat.
Option (a) is correct because the reaction between sodium and alcohol is indeed exothermic, releasing heat as hydrogen gas is produced. Options (b), (c), and (d) are incorrect; increasing temperature does not necessarily speed up this reaction significantly, oxidation state of sodium doesn't change, and it's not a typical displacement reaction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of converting solid sodium chloride into chlorine gas and hydrogen gas is known as:
सही उत्तर: घ) 4. Combustion
Electrolysis involves the decomposition of a compound using electric current. In this case, NaCl is decomposed into Cl₂ and H₂ when an electric current is passed through it with appropriate electrodes. The other options represent different chemical reactions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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