GK
CHEMISTRY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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change in color or odor
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change in state
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foaming or bubbling
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production of heat or light
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Detailed explanation-1: -Color. The changing of color of a substance is not necessarily an indicator of a chemical change.
Detailed explanation-2: -Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.
Detailed explanation-3: -Potential signs that chemical reactions have occurred include a change in color, change in temperature, formation of a gas, and formation of a precipitate.
Detailed explanation-4: -The correct answer is Freezing of water. Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. Freezing of water is not a chemical change as ice when melt changes back to water showing the physical change.
Detailed explanation-5: -Bubbles of gas appear. Gas-producing reactions run to completion when the gas can leave the reaction mixture. A precipitate forms. A color change occurs. The temperature changes. Light is emitted. A change in volume occurs. A change in electrical conductivity occurs. A change in melting point or boiling point occurs. More items