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 boiling point elevation constant, Kb, is related to the change in vapor pressure of a solution. Which of the following correctly states this relationship? (a) Kb = ΔT/m (b) Kb = -ΔT/m (c) Kb = ΔT * m (d) Kb is independent of temperature
सही उत्तर: क) (a) Kb = ΔT/m
Kb represents the molar mass (m) times the change in temperature (ΔT). The equation Kb = ΔT/m directly reflects this relationship. Options (b), (c), and (d) present incorrect relationships or a misunderstanding of the concept.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following statements regarding the solubility product constant (Ksp) for AgCl is correct? (a) Ksp = [Ag⁺][Cl⁻] (b) Ksp = 1/[Ag⁺][Cl⁻] (c) Ksp = [AgCl] (d) Ksp is independent of concentration
सही उत्तर: घ) (d) Ksp is independent of concentration
The solubility product constant (Ksp) expresses the equilibrium concentrations of a sparingly soluble ionic compound. For AgCl, it’s defined as Ksp = [Ag⁺][Cl⁻]. Option (a) accurately represents this relationship. Options (b), (c), and (d) are incorrect interpretations or misapplications of the concept.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction of ethanol with excess HI produces which of the following major products? (a) Ethyl iodide (b) Ethanoic acid (c) Vinyl iodine (d) Ethyl hydrogen iodide
सही उत्तर: क) (a) Ethyl iodide
The reaction of ethanol with excess HI is a standard example of a substitution reaction where the -OH group is replaced by an -I group. Option (a), ethyl iodide, is the major product formed due to this substitution. Options (b), (c), and (d) represent alternative reactions that would occur under different conditions.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The molar mass of CO₂ is 44 g/mol. If you have 33 grams of CO₂, how many moles are present?
सही उत्तर: ख) 1 mol
Moles = Mass / Molar mass. Therefore, moles = 33 g / 44 g/mol = 0.75 mol. Option 2 is correct because it uses the correct calculation. Option 3 is incorrect as its value is too large and option 4 is completely wrong.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which of the following compounds will give a positive Tollens' reagent test (silver mirror)?
सही उत्तर: क) Ethane
A positive Tollens’ reagent test indicates the presence of an aldehyde. Ethanol (C₂H₅OH) is an alcohol and does not react; Ethane and Dimethyl ether are alkanes. Ethene undergoes oxidation in basic solution forming a carbon dioxide that reacts with silver ions to form a silver mirror, resulting in a positive Tollens’ reagent test. Therefore, the correct answer is Ethanol.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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One mole of electrons carries a charge of approximately 96,485 Coulombs (F = 96,485 C/mol). What is the equivalent mass (in grams) of one mole of electrons?
सही उत्तर: क) 0.5 g
Equivalent mass = Charge / Voltage. In this case, the charge is 96,485 C and the voltage (potential difference) is defined by one mole of electrons. Therefore, equivalent mass = 96,485 C / 96,485 C/mol = 1 g. Option 2 is wrong as it contains incorrect numerical values, options 3 and 4 are irrelevant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A gas occupies a volume of 5L at room temperature (298K) and pressure of 1 atm. If the pressure is increased to 2 atm while maintaining the same temperature, what will be the new volume? (Assume ideal gas behavior)
सही उत्तर: क) 2.5 L
According to Boyle's Law (at constant temperature), P₁V₁ = P₂V₂. Therefore, V₂ = (P₁V₁) / P₂ = (1 atm * 5L) / 2 atm = 2.5 L. Option 2 is incorrect as it keeps the volume the same and doesn’t apply Boyle's Law. Options 3 and 4 are much larger increases than expected.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The rate law for the reaction 2NO(g) + O₂(g) → 2NO₂(g) is found to be Rate = k[NO]²[O₂]. What is the overall order of this reaction?
सही उत्तर: क) 1
The rate law has the form Rate = k[NO]²[O₂], where the exponents are the orders. The overall order is 2 + 1 = 3. Option 1 is incorrect because it doesn't account for the exponents. Option 2 is incorrect as it doesn’t match the observed rate law. Option 3 is correct, and option 4 is an irrelevant constant.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A solution has a pH of 6. What is the concentration of hydroxide ions [OH⁻] in mol/L?
सही उत्तर: घ) 1 x 10⁻⁵ M
pH = -log[H⁺]. Therefore, [H⁺] = 10^(-pH) = 10^(-6). The concentration of hydroxide ions is related to the hydrogen ion concentration by the equation Kw = [H⁺][OH⁻] = 1.0 x 10⁻¹⁴ at 25°C. So [OH⁻] = Kw / [H⁺] = (1.0 x 10⁻¹⁴) / (1.0 x 10⁻⁶) = 1.0 x 10⁻⁸ M or 1 x 10⁻⁸ M. The option “1x 10^-4 M” is not correct, as the concentration should be much smaller.”},{
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The reaction between hydrochloric acid (HCl) and sodium carbonate (Na₂CO₃) produces carbon dioxide gas. What is the volume of carbon dioxide produced when 10 cm³ of HCl reacts completely with excess Na₂CO₃ at STP?
सही उत्तर: ख) 20 cm³
The balanced equation for the reaction is HCl + Na₂CO₃ → NaCl + H₂O + CO₂. According to Avogadro's Law, at STP, 22.4 L of gas occupies one mole. Since HCl reacts completely with excess Na₂CO₃, it produces one mole of CO₂. Therefore, the volume produced will be 22.4L/mole * 1 mole = 22.4 cm³. Closest answer to calculation is 20cm³.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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