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 compounds contains a carbonyl group?
सही उत्तर: ग) C₃H₈O
A carbonyl group is a functional group characterized by a carbon atom double-bonded to an oxygen atom (C=O). C₃H₈O represents Acetone, which has this characteristic.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a redox reaction, what does the oxidation number of an element change by?
सही उत्तर: ख) Decrease
During oxidation, an element loses electrons (increases its oxidation number), while during reduction, it gains electrons (decreases its oxidation number). The overall change reflects this process.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The pH of a solution is 6. What concentration of hydrogen ions (H⁺) exists in mol/L?
सही उत्तर: क) 10⁻⁵ mol/L
pH = -log[H⁺]. Solving for [H⁺], we get [H⁺] = 10⁻⁷ M. This is the same as 10⁻⁵ mol/L.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The rate constant of a chemical reaction is 2.5 x 10⁻³ s⁻¹ at 298 K. What is the order of the reaction with respect to its reactant?
सही उत्तर: क) 1
The rate law for a reaction is given by k = A[X]ⁿ, where k is the rate constant, [X] is the concentration of the reactant, and n is the order of the reaction. Solving for 'n' gives us n = 1/k. Therefore, the order of this reaction is 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molarity of a solution prepared by dissolving 3.6 grams of anhydrous CuSO₄ in 500 mL of water is approximately:
सही उत्तर: ख) 2.0 M
CuSO₄ has a molecular weight of 159.61 g/mol. 3.6 grams corresponds to 3.6 / 159.61 = 0.0223 moles. Diluting 0.0223 moles into 500 mL (0.5 L) results in a concentration of 0.0223 / 0.5 = 0.0446 M, which is closest to 0.04 M. The most tempting answer, 2.0M, arises from an incorrect calculation of the CuSO₄ mass.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements regarding oxidation and reduction reactions is correct? (a) Oxidation always involves a loss of electrons, while reduction always involves a gain of electrons. (b) Oxidation always involves a gain of electrons, while reduction always involves a loss of electrons. (c) Oxidation can involve either a gain or loss of electrons, depending on the species involved. (d) Reduction always involves an increase in energy.
सही उत्तर: क) (a) Oxidation always involves a loss of electrons, while reduction always involves a gain of electrons.
Option (a) is correct. Oxidation is defined as the loss of electrons, and reduction is defined as the gain of electrons. Options (b) reverses this definition. Option (c) describes a more complex scenario, while (d) is factually incorrect about reduction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The addition of a small amount of potassium iodide (KI) to solution containing silver nitrate (AgNO₃) results in the formation of silver iodide (AgI), which precipitates out. This is because: (a) Silver ions are more reactive than iodine ions. (b) KI increases the solubility of AgNO₃ in water. (c) KI provides a source of free iodide ions that react with Ag⁺ to form AgI. (d) The reaction produces heat, which favors the formation of AgI.
सही उत्तर: घ) (d) The reaction produces heat, which favors the formation of AgI.
The addition of KI is a classic precipitation reaction where I⁻ ions displace Ag⁺ ions from solution to form insoluble AgI. Options (a), (b) and (d) are incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements accurately describes the properties of covalent compounds? (a) They are generally strong electrolytes in water. (b) Their intermolecular forces are primarily due to electrostatic attractions between ions. (c) They often exhibit high melting and boiling points. (d) They typically do not conduct electricity when molten or dissolved in polar solvents.
सही उत्तर: घ) (d) They typically do not conduct electricity when molten or dissolved in polar solvents.
Covalent compounds have weak intermolecular forces (primarily Van der Waals forces), leading to low melting and boiling points and generally poor electrical conductivity. Options (a) and (b) describe ionic compounds, while option (c) describes metallic solids.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction of potassium permanganate (KMnO₄) with sodium carbonate (Na₂CO₃) in acidic solution produces: (a) Carbon monoxide and water (b) Carbon dioxide, water and manganese ions (c) Sodium oxide and carbon dioxide (d) Potassium hydroxide and manganese dioxide
सही उत्तर: ख) (b) Carbon dioxide, water and manganese ions
The reaction of KMnO₄ with Na₂CO₃ in acidic conditions leads to the formation of CO₂, H₂O, and Mn²⁺ ions. Option (a) is incorrect because it doesn't account for the gaseous product. Option (c) is wrong as sodium oxide isn’t produced. Option (d) incorrectly identifies a different product.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The process of converting a solid metal oxide into the corresponding metal and oxygen gas upon heating is called:
सही उत्तर: ख) Decomposition
The term 'decomposition' accurately describes this chemical transformation. Heating metal oxides breaks them down into their elemental components, namely the metal and oxygen. The other options – neutralization (acid-base reaction), redox reaction (electron transfer), and sublimation (solid directly to gas) – do not fit this specific scenario.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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