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
-
Which of the following statements accurately describes Brass? (a) A compound formed by heating copper and tin (b) An alloy primarily composed of copper and zinc (c) A ceramic material derived from clay minerals (d) A pure element with metallic properties
सही उत्तर: ख) (b) An alloy primarily composed of copper and zinc
Brass is a well-known alloy. It’s comprised predominantly of Copper and Zinc. Option (a) describes a chemical reaction rather than an alloy formation; (c) defines ceramic material, and (d) specifies a single pure metal.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Milk of magnesia, used as an antacid, is a suspension of: (a) A homogeneous mixture (b) Solid particles dispersed in a liquid medium (c) A chemical reaction between magnesium and hydrochloric acid (d) Pure magnesium hydroxide solution
सही उत्तर: ख) (b) Solid particles dispersed in a liquid medium
Milk of magnesia is a suspension – it contains solid magnesium hydroxide particles dispersed in water. The other options describe different types of mixtures or chemical reactions. Option (a) is incorrect because suspensions are not homogeneous.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the primary role of nitrates (NO₃⁻) in plant nutrition?
सही उत्तर: ग) Serving as a source of nitrogen for protein synthesis and chlorophyll production.
Nitrates are the main form in which nitrogen is absorbed by plant roots. They are crucial components of amino acids and chlorophyll, essential for growth and photosynthesis.”} , 3, 4} 5
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The pH value of a solution is a measure of its _____.
सही उत्तर: ग) acidity or alkalinity (sourness or bitterness)
pH stands for ‘potential of Hydrogen’ and it quantifies the concentration of hydrogen ions (H⁺) in a solution. Thus, it directly reflects whether a substance is acidic or alkaline.”} , 3, 4} 5
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The decomposition of potassium chlorate (KClO₃) can be represented as: 2 KClO₃ → 2 KCl + 3 O₂. If 10g of KClO₃ is heated, what mass of oxygen gas will be produced?
सही उत्तर: ख) 8.6 g
First, calculate the molar mass of KClO₃ (39.1 + 35.5 + 3 * 16) = 122.6 g/mol. Calculate moles of KClO₃ (10g / 122.6g/mol ≈ 0.082 mol). From the balanced equation, 3 moles of O₂ are produced for every 2 moles of KClO₃. Therefore, 3 * 0.082 = 0.246 mol of O₂ is produced. Convert moles to grams (0.246 mol * 32g/mol ≈ 7.9 g). The correct answer should be close to the calculated value of oxygen production.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the molecular formula of glucose (C₆H₁₂O₆) when reduced to its simplest form?
सही उत्तर: क) CH₂O
Reducing the molecular formula C₆H₁₂O₆ to its simplest form involves dividing by their greatest common divisor. The GCD of 6, 12, and 6 is 6. Dividing each subscript by 6 gives us CH₂O. Options suggesting higher numbers are incorrect because they don't reflect the most reduced state.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What volume of oxygen gas (O₂) at STP (Standard Temperature and Pressure) is produced from the complete combustion of 44 g of ethane (C₂H₆)?
सही उत्तर: ख) 16g
The balanced equation for the reaction is C₂H₆ + 3O₂ → 2CO₂ + 6H₂O. To determine the volume of O₂, we first calculate moles of ethane (44g / 30g/mol = 1.47 mol). Then, using the stoichiometry of the reaction, 3 moles of O₂ are produced for every 1 mole of ethane. Therefore, 1.47 moles of O₂ is produced. At STP, 1 mole of any gas occupies 22.4L. So, volume = 1.47 mol * 22.4 L/mol = approximately 33.4 L. Option 16g does not match this calculation.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the oxidation number of sulfur in H₂SO₄?
सही उत्तर: ख) +6
In H₂SO₄, sulfur has a +6 oxidation state. Oxygen typically has -2, and since there are two oxygen atoms, their contribution is -4. The hydrogen atoms contribute +2. Therefore, the overall charge is 0 (+2 - 4 = -2, which cancels out with the two hydrogens). The most tempting option (+2) arises from considering only the sulfate ion, ignoring the hydrogen.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The mass percentage of oxygen in H₂O₂ is calculated as follows. If 23 g of H₂O₂ are dissolved in 100 g of water, what is the mass percentage of oxygen (O) in the solution? (Atomic masses: H = 1, O = 16)
सही उत्तर: ख) 16.00%
The formula for calculating percentage composition is (mass of element / mass of compound) * 100%. In H₂O₂, the mass of oxygen is 2 * 16 = 32 g, and the mass of the compound is 2 * 1 + 2 * 16 = 34 g. Therefore, (32/34)*100% = 94.12%. The most tempting option (8.16%) arises from a misunderstanding of the calculation – it’s not directly calculating oxygen percentage but rather how much of the compound is oxygen.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the pH value of a solution containing [H⁺] = 1 × 10⁻⁵ M?
सही उत्तर: क) 5
pH is defined as -log[H⁺]. Therefore, pH = -log(1 × 10⁻⁵) = 5. The other options represent incorrect calculations or assumptions about the pH scale.
💬 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।