रसायन विज्ञान (Chemistry) – Chemistry MCQ

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

31. The enthalpy change (ΔH) for the reaction CaCO₃(s) → CaO(s) + CO₂(g) is approximately -178 kJ/mol. Which of the following statements regarding this process is correct?

    कIt indicates an endothermic reaction as heat is absorbed खIt indicates an exothermic reaction as heat is released गThe magnitude of ΔH is irrelevant in determining if the reaction is exothermic or endothermic घThe reaction rate increases proportionally with increasing temperature
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32. Which of the following compounds will exhibit maximum ionization enthalpy?

    कN₂ खO₂ गF₂ घCl₂
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33. The molar mass of H₂O is 18 g/mol. If 36g of H₂O is dissolved in water, the number of moles of H₂O present will be approximately:

    क0.5 mol ख1 mol ग2 mol घ4 mol
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34. Which of the following statements accurately describes the relationship between acidity and ionization constant (Ka) for weak acids?

    कAs Ka increases, the acid is weaker खAs Ka decreases, the acid is stronger गKa has no direct correlation with acid strength घKa indicates the concentration of hydrogen ions (H⁺)
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35. The heat of hydration of NaCl is approximately equal to the heat of solution of which of the following salts?

    कSodium chloride (NaCl) खPotassium nitrate (KNO₃) गMagnesium sulphate (MgSO₄) घAmmonium chloride (NH₄Cl)
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36. A student performs an experiment to determine the solubility of lead(II) chloride (PbCl₂) in water at room temperature. They observe that the solution becomes cloudy after a certain time and measure the concentration of Pb²⁺ ions in the supernatant (top layer). What is the primary factor influencing the observed change?

    कThe decrease in temperature खAn increase in the ionic strength of the solution गThe formation of a gas bubble घThe addition of an oxidizing agent
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37. The pH of 0.1 M hydrofluoric acid (HF) solution is best approximated by:

    क0 ख2 ग7 घ14
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38. The reaction of a Grignard reagent (RMgX) with dimethylformamide (DMF), followed by hydrolysis, yields:

    कan alkane खa ketone गan alcohol घan ester
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39. The rate of a reaction increases by a factor of e when the temperature is raised from 25°C to 35°C. The activation energy for this reaction is approximately:

    क10 kJ/mol ख100 kJ/mol ग273 kJ/mol घ400 kJ/mol
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40. Carborundum (silicon carbide, SiC) is a widely used abrasive material. Its hardness stems primarily from:

    कIts amorphous structure खThe strong covalent bonding between silicon and carbon atoms गIts high electrical conductivity घIts ability to form stable solutions
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