Just question Q4 with explanations as to why these carbohydrates are the answer.

Question

Just question Q4 with explanations as to why these carbohydrates are the answer. Thank you.

SDFGHKL Laboratory ? Sheet- Lab 16 C. lodine Test for Polysaccharides 0.3 From the results in Part C, which carboh drates are polysaccharides? Q.4 What carbohydrsets) would give the following test results? a. Produce a reddish-orange solid with Benedict's reagent and a red coloe with Seliwanoffs reagent. Why? b. Produces no color change with Renedict's or Seliwanoff's reagent, but turns a blue-black color with iodine reagent. Why? Q5 Indicale whthyrates wl gihe a positlive () or negative (-) result in each of the tests listed below Carbohydrate Benediet's Test SeliwanofTs Test lodine Test Lactose Maltose Amylose

Explanation / Answer

4. (a) As we know that Benedict's test is used to find reducing (free) aldehyde and ketone. Positive results from the above test confirm the free ketone or aldehyde group in the carbohydrates.

Now, the second test, Seliwanoff's is also given the positive result which tells about the presence of ketohexoses.

Hence, the carbohydrate is fructose.

(b) Both the above test shows the negative results means there is no free aldehyde and Ketone group present. So, it is not a reducing sugar. Non-reducing sugars present here are sucrose and starch.

It is also given that it will give a blue-black color with the iodine. Among these two sugars, the only starch will give the blue-black color with iodine.

Hence, the carbohydrate is starch.

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