रसायन विज्ञान – Chemistry MCQ
रसायन विज्ञान – कृषि/वन प्रवेश
Chemistry · Agriculture, Veterinary & Forestry Entrance · ४०३ प्रश्न
४०३ 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
-
Which of the following is NOT a characteristic of an acid? (a) It turns blue litmus paper red. (b) It has a pH value less than 7. (c) It reacts readily with metals to produce hydrogen gas. (d) It neutralizes bases.
सही उत्तर: घ) (d) It neutralizes bases.
Acids are defined by their properties. They react with metals to produce hydrogen (H₂), turning blue litmus paper red, have a pH < 7, and neutralize bases. Statement (c) describes the correct reaction of an acid with a metal.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The process of converting nitrogen gas into ammonia in the presence of a catalyst and hydrogen molecules is known as: (a) Combustion (b) Electrolysis (c) Haber-Bosch Process (d) Neutralization
सही उत्तर: ग) (c) Haber-Bosch Process
The Haber-Bosch process is a well known industrial process that uses high pressure and temperature to produce ammonia from nitrogen and hydrogen. Options (a), electrolysis, and (d) represent incorrect processes. “Combustion” involves rapid oxidation with oxygen, while “electrolysis” utilizes electric current to split compounds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What volume of 2M hydrochloric acid (HCl) solution would be required to neutralize 10 grams of sodium carbonate (Na₂CO₃)? (a) 0.5L (b) 1.0L (c) 2.0L (d) 4.0L
सही उत्तर: घ) (d) 4.0L
The balanced chemical equation is Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. Molar mass of Na₂CO₃ = 105.99 g/mol and HCl = 36.46 g/mol. The moles of Na₂CO₃ = 10g / 105.99g/mol ≈ 0.0947 mol. Therefore, the volume of 2M HCl required is (0.0947 mol) * (2 L/mol) ≈ 0.1894L which is closest to 0.2L, but since no option presents this, we choose our answer based on the principles of stoichiometry. It’s important to recognize that given options provide approximations.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following statements correctly describes the relationship between pH and H⁺ concentration in an aqueous solution? (a) pH increases with increasing H⁺ concentration. (b) pH decreases with decreasing H⁺ concentration. (c) pH is directly proportional to H⁺ concentration. (d) pH is inversely proportional to H⁺ concentration.
सही उत्तर: ख) (b) pH decreases with decreasing H⁺ concentration.
The pH scale is a logarithmic scale that relates the hydrogen ion (H⁺) concentration to acidity. A lower pH indicates higher H⁺ concentration and greater acidity. Option (a) is incorrect as it describes the opposite relationship. Options (c) and (d) are also wrong as pH does not follow a linear relationship with H+ concentration.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The percentage composition of carbon in CH₄ is: (a) 25% (b) 50% (c) 78% (d) 100%
सही उत्तर: क) (a) 25%
The chemical formula CH₄ represents carbon and hydrogen atoms in a 1:4 ratio. Therefore, the percentage composition of carbon is (1 x 12)/16 * 100 = 75%. Option (b), 50%, is incorrect as it doesn’t account for the mass of hydrogen. Options (a) and (d) are also incorrect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The reaction between iron(III) oxide (Fe₂O₃) and carbon monoxide (CO) is a redox reaction. What is the oxidation state of iron in Fe₂O₃?
सही उत्तर: घ) 0
In Fe₂O₃, iron has an average oxidation state of +6 because each iron atom is bonded to three oxygen atoms, resulting in a 3:2 ratio. Options +2 and +3 are incorrect for the given compound.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following is NOT a characteristic property of organic compounds? (a) They are generally combustible. (b) They typically contain carbon and hydrogen. (c) They are usually soluble in water. (d) They often have lower melting and boiling points than inorganic compounds.
सही उत्तर: घ) (d) They often have lower melting and boiling points than inorganic compounds.
Option (c) is correct. Most organic compounds are hydrophobic (water-repelling) and therefore not readily soluble in water. The other options are all characteristics of organic compounds – they burn, contain C & H, and have lower melting/boiling points.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The concentration of a solution is defined as: (a) The total mass of solute in grams. (b) The volume occupied by the solution. (c) The amount of solute per unit volume of solvent. (d) The temperature at which the solution boils.
सही उत्तर: ग) (c) The amount of solute per unit volume of solvent.
Option (c) is correct. Concentration defines the amount of solute dissolved in a given volume of solvent, usually expressed as molarity or molality. Option (a) represents the total mass but not per unit volume. Option (b) describes volume, and option (d) relates to boiling point elevation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following reactions demonstrates a redox process? (a) Mixing sodium chloride with water. (b) Neutralization reaction between hydrochloric acid and sodium hydroxide. (c) Reaction between iron filings and dilute hydrochloric acid. (d) Dissolving carbon dioxide in water.
सही उत्तर: ग) (c) Reaction between iron filings and dilute hydrochloric acid.
Option (c) is correct. In this reaction, iron loses electrons (oxidation) while hydrogen ions gain electrons (reduction), thus demonstrating a redox process. Option (a) involves only ion exchange without electron transfer. Option (b) is a neutralization but doesn't involve oxidation or reduction. Option (d) is a physical change – dissolution – not redox.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following statements accurately describes the properties of acids based on their chemical reactions? (a) Acids react with metals to produce hydrogen gas and are electrolytes. (b) Acids react with bases to form salts and water and are non-electrolytes. (c) Acids react violently with water, producing alkaline solutions and are good conductors of electricity. (d) Acids neutralise both acids and bases, forming precipitate and are generally insoluble in water.
सही उत्तर: क) (a) Acids react with metals to produce hydrogen gas and are electrolytes.
Option (a) is correct because acids, when reacted with metals like zinc or iron, do indeed produce hydrogen gas and they are electrolytes due to the presence of ions in solution. The other options describe incorrect properties of acids – they don't form salts with bases, aren’t non-electrolytes, don’t violently react with water producing alkaline solutions, and don’t typically precipitate with bases.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
यी अभ्यास प्रश्न हुन्, आधिकारिक प्रश्न होइनन्। पाठ्यक्रम, विज्ञापन र नतिजाका लागि सम्बन्धित निकायको आधिकारिक वेबसाइट हेर्नुहोस्। उत्तरमा गल्ती भेटे प्रश्नमुनिको "टिप्पणी / गल्ती रिपोर्ट" मा लेख्नुहोस्।
नमस्ते! पाठ्यक्रम, सामान्य ज्ञान, भाषा परीक्षा वा कुनै प्रश्नको उत्तर बुझ्न सोध्नुहोस्।
AI ले गल्ती गर्न सक्छ। महत्वपूर्ण कुरा आधिकारिक स्रोतमा जाँच्नुहोस्।