A. Fe2O3 + 3CO= 2Fe+3CO2
Here element oxidised is CO or Carbon Monoxide, since oxygen is added.
B. 2HCl+2KMnO4+3H2C2O4=6CO2+2MnO2+2KCl+4H2O
Here Element reduced is 3H2C2O4, since Hydrogen is being added. Also KMnO4 is reduced, since Oxygen is removed.
4. NaOH
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Each isotope has a unique rate of decay, making them suitable for determining the dates of ancient artifacts. The answer is "rate of decay of the isotope."
The elements in a periodic table are arranged in the increasing order of their atomic number.