The `COD` value of a water sample is 40 ppm. Calculate the amount of acidified `K_(2) Cr_(2) O_(7)` required to oxidise the organic matter present in 500 ml of that water sample.

Explanation

To solve the problem of calculating the amount of acidified \( K_2Cr_2O_7 \) required to oxidize the organic matter present in a 500 ml water sample with a COD value of 40 ppm, we can follow these steps:

### Step 1: Understand the COD Value
The Chemical Oxygen Demand (COD) value of 40 ppm means that in 1 million grams (or 1,000 liters) of water, there are 40 grams of oxygen required to oxidize the organic matter.

### Step 2: Calculate the Amount of Oxygen Required for 500 ml
Since 1 ppm is equivalent to 1 mg of substance per liter of solution, we can convert the COD value to the amount of oxygen needed for 500 ml of water.

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