Question

Change can be observed by their effect . Explain by giving suitable example

Answer 1

Answer:

A chemical reaction can be identified by:

• Change of state of a substance. (ex Ammonia gas reacts with hydrogen chloride gas to produce solid ammonium chloride.)
• Change of color of a substance. (ex: Copper reacts with oxygen, H2O and CO2 to give copper carbonate, which changes color from brown to blue or blue green.)
• Production of Heat and Light. (ex: combustion reactions usually release heat)
• Evolution of gas(ex: when metals react with acids hydrogen gas is released)

Answer 2

Answer:

Zn+HCL---- ZnCL2 + H2

Explanation:

A COLOURLESS ODOURLESS GAS EVEOLVES WITH A POP SOUND AND BURNS WITH A PALE BLUE FLAME WHEN PURE