This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the answers to your questions: 25) A magnesium ribbon should be cleaned before burning in air to remove the layer of magnesium oxide (MgO) that forms on its surface. This oxide layer is relatively unreactive and prevents the magnesium from readily reacting with oxygen during combustion. 26) i) Compound 'X' is iron(III) oxide (Fe_2O_3). ii) The reaction is called the Thermite reaction. The balanced chemical equation is: Fe_2O_3(s) + 2Al(s) → 2Fe(l) + Al_2O_3(s) + Heat 27) • Arteries carry oxygenated blood away from the heart to the body, while veins carry deoxygenated blood back to the heart. • Arteries have thick, elastic, muscular walls to withstand high pressure, whereas veins have thinner walls and contain valves to prevent backflow of blood. 28) B) Four organs of the Human excretory system are: • Kidneys • Ureters • Urinary bladder • Urethra 29) i) Amoeba: Binary fission ii) Planaria: Regeneration 30) Planets do not twinkle because they are much closer to Earth than stars and appear as extended sources of light. The light from a planet is considered a collection of many point sources. Any atmospheric turbulence that might cause one part of the planet's light to dim is compensated by another part brightening, resulting in a steady, non-twinkling appearance. 31) Step 1: Identify the given values. Voltage, V = 220 V Current, I = 0.50 A Step 2: Use the formula for power. The power (P) of an electric bulb is given by the product of voltage (V) and current (I): P = V × I Step 3: Substitute the values and calculate the power. P = 220 V × 0.50 A P = 110 W The power of the bulb is 110 W. 32) The resistance of a conductor depends on the following factors: • Length of the conductor (Resistance is directly proportional to length). • Area of cross-section of the conductor (Resistance is inversely proportional to the area of cross-section). • Nature of the material of the conductor (Different materials have different resistivities). • Temperature of the conductor (Resistance generally increases with temperature for metals). That's 2 down. 3 left today — send the next one.