Virtual Labs

Chemical composition of cement

Which oxide in cement is primarily responsible for strength development?

a: Fe₂O₃ Explanation

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b: Al₂O₃ Explanation

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c: CaO Explanation

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d: MgO Explanation

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What is the role of SO₃ in cement composition?

a: Enhances early strength Explanation

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b: Prevents flash setting Explanation

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c: Increases workability Explanation

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d: Improves color Explanation

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Which oxide in cement contributes to early strength and lowers clinkering temperature?

a: SiO₂ Explanation

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b: Al₂O₃ Explanation

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c: Fe₂O₃ Explanation

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d: MgO Explanation

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Which oxide helps in preventing alkali-silica reaction (ASR)?

a: Na₂O Explanation

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b: K₂O Explanation

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c: SO₃ Explanation

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d: Both a & b Explanation

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What is the main function of Fe₂O₃ in cement?

a: Enhances strength Explanation

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b: Controls setting time Explanation

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c: Assists in clinker formation and impacts color Explanation

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d: Prevents expansion Explanation

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What is the purpose of adding ammonium oxalate ((NH₄)₂C₂O₄) during the determination of CaO?

a: To precipitate calcium oxalate Explanation

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b: To dissolve calcium Explanation

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c: To remove impurities Explanation

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d: To neutralize the solution Explanation

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Why is nitric acid (HNO₃) used in the determination of SiO₂ in cement?

a: To dissolve calcium oxide Explanation

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b: To enhance filtration Explanation

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c: To acidify the solution and convert silica into insoluble form Explanation

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d: To precipitate iron oxide Explanation

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What is the key method for determining the percentage of Fe₂O₃ in cement?

a: Titration using KMnO₄ Explanation

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b: Gravimetric analysis Explanation

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c: Filtration and drying Explanation

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d: Spectrophotometry Explanation

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What compound is precipitated to determine the MgO content in cement?

a: Magnesium hydroxide Explanation

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b: Magnesium ammonium phosphate (MgNH₄PO₄) Explanation

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c: Magnesium sulfate Explanation

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d: Magnesium carbonate Explanation

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What is the function of tetracalcium aluminoferrite (C₄AF) in cement?

a: Increases strength significantly Explanation

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b: Improves workability but contributes minimal strength Explanation

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c: Reduces hydration heat Explanation

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d: Prevents sulfate attack Explanation

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What is the main reason for using low-heat cement in mass concrete structures?

a: It prevents rapid strength gain Explanation

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b: It reduces the risk of thermal cracking Explanation

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c: It increases hydration rate Explanation

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d: It improves alkali resistance Explanation

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