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Standard VII

Biology

Test for Adulteration in Milk

Question 1 Gi...

Question

Question 1
Given below from (i) to (iv) are some food items.
(i) Boiled and mashed potato
(ii) Glucose solution
(iii) A slice of bread
(iv) Mustard oil
Which of the above will give a blue-black color when tested with iodine?
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)

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Solution

An answer is option (b).

Iodine gives a blue-black colour with starch. The iodine test is used to identify the presence of starch in a food item. Potato is rich in starch, a type of carbohydrate. Also, bread is a good source of starch. So, when drops of iodine solution are poured on the surface of bread or potato, you will be able to see a blue-black colour on the surface of the food item. This blue-black colour indicates the presence of starch.

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Similar questions

Q. Question 1
Given below from (i) to (iv) are some food items.

(i) Boiled and mashed potato
(ii) Glucose solution
(iii) A slice of bread
(iv) Mustard oil

Which of the above will give blue-black colour when tested with iodine?

(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)

Question 4

Read the food items given below.

(i) Wheat

(ii) Ghee

(iii) Iodised salt

(iv) Spinach

Which of the above food items are "energy giving foods"?

(a) (i) and (iv)

(b) (ii) and (iv)

(d) (iii) and (iv)

Q. The following foods were tested for starch using iodine. The results are shown below:

Food stuff	Colour
rice	blue-black
cucumber	no colour change
onion	no colour change
dal	blue-black

Which of the following foods contains starch?
(i) rice + dal
(ii) rice + cucumber
(iii) only rice
(iv) dal + onion

(a) only i
(b) i, ii, iii, and iv
(c) i, ii, and iii
(d) i, iii and iv

Given below are the steps to test the presence of proteins in a food item.

(i) Take a small quantity of the food item in a test tube, add 10 drops of water to it and shake it.

(ii) Make a paste or powder of food to be tested.

(iii) Add 10 drops of caustic soda solution to the test tube and shake well.

(iv) Add 2 drops of copper sulphate solution to it.

Which of the following is the correct sequence of steps?

(a) i, ii, iv, iii

(b) ii, i, iv, iii

(d) iv, ii, i, iii

Question 1

Given below are the names of some animals.

(i) Goat

(ii) Human beings

(iii) Cockroach

(iv) Eagle

Which of the above animals form a pair of omnivores?

(a) (i) and (ii)

(b) (ii) and (iii)

(d) (ii) and (iv)

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Test for Adulteration in Milk

Standard VII Biology

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Question 1Given below from (i) to (iv) are some food items.(i) Boiled and mashed potato(ii) Glucose solution (iii) A slice of bread(iv) Mustard oilWhich of the above will give a blue-black color when tested with iodine?(a) (i) and (ii)(b) (i) and (iii)(c) (ii) and (iii)(d) (iii) and (iv)

Question 1
Given below from (i) to (iv) are some food items.
(i) Boiled and mashed potato
(ii) Glucose solution
(iii) A slice of bread
(iv) Mustard oil
Which of the above will give a blue-black color when tested with iodine?
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)