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 processes contributes most to the formation of nitric acid (HNO₃) in atmospheric pollution?
सही उत्तर: ख) B. Combustion of fossil fuels, particularly nitrogen-containing compounds.
The oxidation of nitrogen oxides (NOx) produced during the burning of fossil fuels creates nitric acid. This is a major contributor to acid rain. Option A describes photosynthesis; C refers to sulfur dioxide emissions, and D relates to rock weathering.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the primary purpose of adding lime (CaO) to acidic soils?
सही उत्तर: ख) B. To reduce soil acidity by neutralizing hydrogen ions.
Lime (calcium oxide) neutralizes excess hydrogen ions (H+) in acidic soils, raising the pH and increasing nutrient availability, especially phosphorus. Option A is incorrect as lime doesn’t directly affect phosphate solubility; B accurately describes its primary function; C is a secondary effect; and D focuses on potassium.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The process of converting nitrogen gas into ammonia is called:
सही उत्तर: ग) Nitrogen fixation
Nitrogen fixation refers to the conversion of atmospheric nitrogen (N₂) into a usable form, primarily ammonia (NH₃), often catalyzed by microorganisms. Combustion involves burning; oxidation involves adding oxygen; and decomposition is breaking down existing compounds.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The correct formula for calculating the molar mass of a compound is:
सही उत्तर: ख) (Atomic mass of element 1) + (Atomic mass of element 2)
Molar mass is calculated by summing the atomic masses of all atoms present in the chemical formula. The other options describe different calculations or units. Using the sum of atomic masses gives the molar mass in grams per mole (g/mol).
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
What is the primary reason for the color observed when burning magnesium metal?
सही उत्तर: क) Formation of a complex oxide
Burning magnesium produces magnesium oxide (MgO), which has a characteristic bright white color. The other options don’t explain the intense visual effect. The formation of MgO is key to understanding the observed color.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The reaction between sodium hydroxide (NaOH) and carbon dioxide (CO₂) produces which substance?
सही उत्तर: क) Sodium carbonate (Na₂CO₃), Sodium bicarbonate(NaHCO₃) and water (H₂O)
The reaction between sodium hydroxide (NaOH) and carbon dioxide (CO₂) produces sodium bicarbonate. This is a classic acid-base neutralization reaction where CO₂ acts as an acidic component.”} 0.5,
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following statements accurately describes the difference between a strong acid and a weak acid?
सही उत्तर: ख) Weak acids have a higher Ka value than strong acids; both are fully ionized in solution
The defining characteristic is the extent of dissociation. Strong acids fully dissociate, releasing most H₃O⁺ ions, while weak acids only partially dissociate. The Ka value relates to equilibrium constants but doesn’t directly explain the degree of ionization.”} 0.5,
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
The oxidation number of chromium (Cr) in K₂Cr₂O₇ (potassium dichromate) is:
सही उत्तर: घ) +7
In K₂Cr₂O₇, chromium has a +6 oxidation state. This can be determined by balancing the charges of the ions present. The other options represent incorrect oxidation states for chromium in this compound based on standard redox reactions.”} 0.5,
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Which of the following solutions would exhibit the highest pH value?
सही उत्तर: घ) 1 M NH₃
Strong bases increase pH values. NH₃ (ammonia) is a weak base and will produce a basic solution with a higher pH than the others which are either neutral or acidic. NaCl, HCl, and H₂SO₄ are all strong acids or neutral salts, resulting in lower pH values.”} 0.5,
💬 टिप्पणी / गल्ती रिपोर्ट (०)
-
Approximately what percentage of the Earth’s crust is composed of iron?
सही उत्तर: घ) 80%
Iron is the most abundant metal in the Earth's crust, making up approximately 70-72%. This reflects the significant presence of iron oxides and silicates within the planet’s geological makeup.
💬 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।