रसायन विज्ञान – Chemistry MCQ
रसायन विज्ञान – कृषि/वन प्रवेश
Chemistry · Agriculture, Veterinary & Forestry Entrance · ४०९ प्रश्न
४०९ 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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What is the chemical formula for iron(III) oxide? (a) Fe₂O₃ (b) Fe₃O₂ (c) FeO (d) Fe₂O
सही उत्तर: क) Fe₂O₃
Option (a) is correct. Iron(III) oxide refers to iron with a +3 oxidation state, represented as Fe³⁺. The formula indicates three oxygen atoms balanced with three iron ions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The pH of a solution is a measure of its ____. (a) color (b) temperature (c) acidity or alkalinity (d) density
सही उत्तर: ग) acidity or alkalinity
Option (c) is correct; pH measures the concentration of hydrogen ions in a solution, which directly relates to its acidity or alkalinity. The other options are unrelated to pH.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following is a strong oxidizing agent? (a) Sodium chloride (NaCl). (b) Carbon dioxide (CO₂). (c) Potassium permanganate (KMnO₄). (d) Glucose (C₆H₁₂O₆).
सही उत्तर: ग) Potassium permanganate (KMnO₄).
Option (c) is correct because potassium permanganate (KMnO₄) is a powerful oxidizing agent. It readily accepts electrons in redox reactions. The other options are neutral or reducing agents.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The decomposition of hydrogen peroxide (H₂O₂) catalyzed by manganese dioxide (MnO₂) produces which of the following? (a) Water and oxygen. (b) Hydrogen and oxygen. (c) Carbon dioxide and water. (d) Nitrogen and oxygen.
सही उत्तर: क) Water and oxygen.
Option (a) is correct; the decomposition of hydrogen peroxide catalyzed by manganese dioxide produces water and oxygen. The other options represent different chemical reactions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements best describes the process of neutralization in chemistry? (a) A reaction where an acid reacts with a base to form a salt and water. (b) A reaction where two acids react to produce a salt and water. (c) A reaction where a base reacts directly with oxygen to form carbon dioxide and water. (d) A spontaneous reaction between a metal and an oxidizing agent.
सही उत्तर: क) A reaction where an acid reacts with a base to form a salt and water.
Option (a) is correct because neutralization involves the reaction of an acid and a base, resulting in a salt and water. The other options describe different types of chemical reactions – (b) is a double displacement reaction, (c) describes combustion, and (d) is oxidation-reduction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements regarding electrolysis of brine (aqueous solution of sodium chloride) is correct?
सही उत्तर: क) Chlorine gas is produced at the cathode and hydrogen gas is produced at the anode.
During electrolysis of brine, chlorine (Cl⁻) gains electrons at the cathode, forming Cl₂ gas. Simultaneously, sodium ions (Na⁺) are reduced at the cathode to form sodium metal. Chloride ions (Cl⁻) are oxidized at the anode, forming oxygen gas (O₂) and hydrogen gas (H₂). The other options describe incorrect processes that occur during the electrolysis of brine.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What volume of 0.5 M solution can be prepared by dissolving 28 grams of anhydrous sodium carbonate (Na₂CO₃) in water?
सही उत्तर: घ) 1000 mL
First, calculate the molar mass of Na₂CO₃: 2(22.99) + 10.6 + 3(16) = 105.99 g/mol. Then, determine the number of moles: 28 / 105.99 ≈ 0.264 moles. Use the formula Molarity = moles / volume to solve for volume: Volume = moles / Molarity = 0.264 / 0.5 = 0.528 L = 528 mL, which is closest to 500mL. The other options are incorrect as they are based on calculations with incorrect molar amounts.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The percentage by mass of chlorine in potassium chlorate, KClO₄, is approximately what?
सही उत्तर: ख) 29%
First calculate the molar mass of KClO₄: 39.1 (K) + 35.5 (Cl) + 4(16) = 122.6 g/mol. Then, calculate the mass of chlorine in one mole of KClO₄: 35.5 g. Finally, find the percentage by mass: (35.5 / 122.6) * 100% ≈ 29%. The other options are incorrect because they result from calculations based on different molar masses or using an incorrect chlorine mass.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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What volume of 6 M H₂SO₄ solution is required to neutralize 50 mL of 3 M NaOH solution?
सही उत्तर: क) 10 mL
The neutralization reaction between H₂SO₄ and NaOH is a 1:1 molar ratio. Therefore, we use the formula: M₁V₁ = M₂V₂. Plugging in the values: (6)(V₁) = (3)(50). Solving for V₁, we get V₁ = 25 mL. The other options are incorrect because they don't follow the correct stoichiometric calculation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The chemical formula for hydrochloric acid (HCl) represents what?
सही उत्तर: ख) A covalent compound containing hydrogen and chlorine atoms.
HCl is a covalent compound where the hydrogen and chlorine atoms are bonded together to form HCl molecules. The ‘H’ represents the hydrogen ion (proton). The other options incorrectly describe the nature of this compound.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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