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When excess of carbon dioxide is passed through lime water, the milkiness disappears because
Passing excess carbon dioxide through lime water initially produces a white precipitate of insoluble calcium carbonate, causing milkiness. On continued bubbling, carbon dioxide dissolves in water to form carbonic acid which reacts with calcium carbonate to yield calcium bicarbonate. Calcium bicarbonRead more
Passing excess carbon dioxide through lime water initially produces a white precipitate of insoluble calcium carbonate, causing milkiness. On continued bubbling, carbon dioxide dissolves in water to form carbonic acid which reacts with calcium carbonate to yield calcium bicarbonate. Calcium bicarbonate is soluble in water, so the precipitate dissolves and the milky appearance disappears. Therefore insoluble calcium carbonate converts to a soluble bicarbonate on excess CO₂, explaining the clearing of lime water in this common laboratory demonstration today. Correct option – B.
See lessIn the reaction of aqueous solution of barium chloride with aqueous solution of sodium sulphate, the aqueous solution formed will be:
When aqueous barium chloride (BaCl₂) reacts with aqueous sodium sulphate (Na₂SO₄), a double displacement reaction occurs producing insoluble barium sulphate (BaSO₄) as a white precipitate and sodium chloride (NaCl) in the aqueous phase. The ionic equation shows Ba²⁺ combining with SO₄²⁻ to form BaSORead more
When aqueous barium chloride (BaCl₂) reacts with aqueous sodium sulphate (Na₂SO₄), a double displacement reaction occurs producing insoluble barium sulphate (BaSO₄) as a white precipitate and sodium chloride (NaCl) in the aqueous phase. The ionic equation shows Ba²⁺ combining with SO₄²⁻ to form BaSO₄(s), while Na⁺ and Cl⁻ remain dissolved as spectator ions producing NaCl(aq). Therefore the aqueous solution after reaction contains sodium chloride, and barium sulphate separates out as a solid under normal laboratory conditions at room. Correct option – D.
See lessAssertion (A): C4H8, C4H6 and C4H10 are members of the same homologous series Reason (R): C4H8, C4H6, C3H4, C3H6, C2H4, C2H2 are unsaturated hydrocarbons.
The assertion is incorrect because members of a homologous series differ by a fixed CH₂ unit and have similar functional groups and general formula. C₄H₁₀ is an alkane (saturated) with formula CnH2n+2, whereas C₄H₈ is an alkene and C₄H₆ an alkyne/diene — both unsaturated and belonging to different hRead more
The assertion is incorrect because members of a homologous series differ by a fixed CH₂ unit and have similar functional groups and general formula. C₄H₁₀ is an alkane (saturated) with formula CnH2n+2, whereas C₄H₈ is an alkene and C₄H₆ an alkyne/diene — both unsaturated and belonging to different homologous series. The reason statement R is true: the listed compounds (C₄H₈, C₄H₆, C₃H₄, C₃H₆, C₂H₄, C₂H₂) are examples of unsaturated hydrocarbons. Therefore, option D is the correct choice here.
See lessHow to score 95 in Class 10 in 2025 and 2026 board exam?
Understand the Syllabus and Blueprint Download the latest CBSE syllabus (2025–26) for all subjects. Note chapter-wise weightage and question paper design from official CBSE sources or Tiwari Academy summaries. Focus on high-weightage topics first and balance easy-scoring chapters. Master NCERRead more
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Practice materials: Assertion–Reason, Case-based, and Objective-type questions as per new CBSE pattern.
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Will CBSE 2025 be easy for Class 10 science?
The CBSE Class 10 Science Exam 2025 is expected to be balanced, with a mix of conceptual, application, and case-based questions. Students who prepare consistently from Tiwari Academy’s NCERT-based study materials, solved sample papers, and mock tests will find the paper manageable and straightforwarRead more
The CBSE Class 10 Science Exam 2025 is expected to be balanced, with a mix of conceptual, application, and case-based questions. Students who prepare consistently from Tiwari Academy’s NCERT-based study materials, solved sample papers, and mock tests will find the paper manageable and straightforward. Tiwari Academy simplifies every topic through short notes, video lessons, and practice questions, ensuring complete understanding. Following its structured guidance can help every student attempt the paper confidently and score above 95% marks in Science.
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