रसायन विज्ञान (Chemistry) – Chemistry MCQ
रसायन विज्ञान (Chemistry) – इन्जिनियरिङ प्रवेश
Chemistry · Engineering Entrance – Mathematics, Physics, Chemistry & English · ७२८ प्रश्न
७२८ 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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According to Werner's theory, the primary valency of a metal in a complex corresponds to its:
सही उत्तर: ख) oxidation state, which is ionisable
Primary valency = oxidation state (satisfied by ionisable anions); secondary valency = coordination number.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The chromyl chloride test is used to detect the presence of:
सही उत्तर: घ) chloride ions
A chloride heated with K₂Cr₂O₇ and conc. H₂SO₄ gives red-orange CrO₂Cl₂ vapour; bromides and iodides do not.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Transition elements show variable oxidation states mainly because:
सही उत्तर: घ) electrons of the (n − 1)d as well as the ns orbitals can take part in bonding
The (n − 1)d and ns energies are close, so different numbers of electrons can be lost.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the Mond process, nickel is purified by converting it into the volatile compound:
सही उत्तर: ख) Ni(CO)₄
Impure Ni reacts with CO at about 330–350 K to form Ni(CO)₄, which decomposes at higher temperature to pure Ni.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In the blast furnace extraction of iron, limestone is added to:
सही उत्तर: ग) remove silica as calcium silicate slag
CaCO₃ decomposes to CaO, which combines with SiO₂ to form fusible CaSiO₃ slag.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Aqua regia is a mixture of concentrated HCl and concentrated HNO₃ in the volume ratio:
सही उत्तर: ख) 3 : 1
Aqua regia, which dissolves gold and platinum, is 3 parts HCl to 1 part HNO₃.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The bleaching action of moist chlorine is due to:
सही उत्तर: घ) oxidation
Cl₂ + H₂O → HCl + HOCl, and HOCl releases nascent oxygen which oxidises the colouring matter.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When concentrated sulphuric acid is added to sugar, the sugar chars and turns black. This shows that the acid is a:
सही उत्तर: क) dehydrating agent
Conc. H₂SO₄ removes the elements of water from C₁₂H₂₂O₁₁, leaving carbon.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Ammonia gas is dried by passing it over:
सही उत्तर: ग) quicklime (CaO)
Being basic, NH₃ reacts with acidic drying agents (H₂SO₄, P₄O₁₀) and forms CaCl₂·8NH₃ with calcium chloride, so CaO is used.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Carbon monoxide is poisonous because it:
सही उत्तर: क) combines with haemoglobin to form a stable carboxyhaemoglobin
CO binds to haemoglobin far more strongly than O₂, reducing the oxygen-carrying capacity of blood.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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