The correct option is (b) Zinc. When dilute sulphuric acid reacts with zinc, it releases hydrogen gas. This colourless gas burns with a pop sound when a burning matchstick is brought near, confirming the presence of hydrogen. Class 10 Science Sample ...
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The correct option is (d) NaHCO₃. Sodium bicarbonate is a mild, non-corrosive base commonly used in baking soda. It is safe, weakly alkaline, and does not harm or corrode, unlike strong bases such as sodium hydroxide or calcium hydroxide. Class 10 ...
The correct option is (b) Colourless. When zinc metal is placed in copper sulphate solution, zinc displaces copper because it is more reactive. The blue colour of copper sulphate fades, turning the solution nearly colourless as zinc sulphate forms. Class 10 ...
(a) Aluminium reacts with dilute HCl in an exothermic reaction, releasing heat and hydrogen gas, causing the temperature to rise. (b) Sodium reacts vigorously with HCl due to its high reactivity, producing hydrogen gas rapidly with heat. (c) Lead reacts ...
(I) Combustion: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O (II) Dehydration: C₂H₅OH →[conc. H₂SO₄, 443 K] C₂H₄ + H₂O (III) Oxidation: C₂H₅OH + [O] → CH₃CHO + H₂O (using acidified K₂Cr₂O₇) CBSE Sample Paper Class 10 Science 2025-26 Tiwari Academy provides CBSE Class 10 ...