Punjab Board Class 10 Science — Flashcards for Quick Revision

A: A chemical reaction is a process where substances change their chemical composition to form new substances. Two key observations that indicate a chemical reaction has occurred are: (1) Change in color

A: Word equation: Magnesium + Oxygen → Magnesium oxide Chemical equation (skeletal): Mg + O₂ → MgO Balanced chemical equation: 2Mg + O₂ → 2MgO Observation: Magnesium burns with a dazzling white flame,

A: The law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. Therefore, the total mass of reactants must equal the total mass of products. In balancing

A: You should suggest BAKING SODA SOLUTION. Reason: Acidity is caused by excess acid in the stomach. Baking soda (sodium hydrogencarbonate, NaHCO₃) is a base that neutralizes the excess acid through a ne

A: Step 1: Test with red litmus paper on all three. Step 2: The one where red litmus turns BLUE = basic solution (base turns red litmus blue). Step 3: The ones where red litmus remains RED = either acidi

A: Acids in curd (lactic acid) react with copper and brass (copper alloy) to form toxic copper compounds that contaminate the food and can cause poisoning. The reaction is: Cu + 2CH₃COOH → Cu(CH₃COO)₂ +

A: Metallic lustre is the shiny, reflective appearance of pure metals. Test: Clean a metal sample with sandpaper and observe its surface. Pure metals like copper, iron, and aluminum show a characteristic

A: This tests MALLEABILITY - the ability to be beaten into thin sheets. Order (decreasing): Lead > Copper > Aluminum > Iron. Malleability varies among metals because different metals have different cryst

A: This demonstrates DUCTILITY - gold's exceptional ductility means its atoms can be stretched and rearranged without breaking. Gold has unique atomic arrangement and bonding that allows extreme stretchi