Parents are advised to discourage their children from eating chips and junk foods due to following reasons:
(i) Junk foods cause obesity
(ii) They may cause loss of appetite.
(iii) They cause mental problems.
(iv) These food items lead to wastage of money.

Our body needs all the nutrients in the right amount, hence we should eat a balanced diet. Vitamin C gets destroyed on heating.

Vitamins are complex organic compounds that are essential for maintaining good health of our body and they also protect us from various diseases. VitaminAkeeps our skin and eyes healthy. Vitamin C helps the body to fight against diseases.

Take a small quantity of food item and wrap it in a piece of paper and crush it. An oily patch on paper shows the presence of fat in that food item.
Starch testing is done by using iodine solution. Appearance of blue black colour shows presence of starch.

It is important to cook food due to following reasons:
(i) Cooking kills various germs present in food items.
(ii) It makes food easily digestible.
(ii) It makes food tasty.

(a) No, fats, proteins and starch are not present in all food items. Some food items have fat, some have protein or starch or some have varying proportions of these nutrients.
(b) Yes, food items such as cooked pulse, milk, groundnut etc contain more than one nutrient.
(c) Yes, food items like a slice of vegetable or fruit do not contain any of these three nutrients.

Our body needs different kinds of food for some special purposes.
For example,

Though minerals and vitamins are needed in very small quantities by our body yet these are important parts of balanced diet because
(i) vitamins are necessary for good eyesight (vitamin-A), growth (vitamin-B₁), keeping teeth gums and joints healthy (vitamin-C) and normal growth of bones (vitamin-D).
(ii) minerals are needed in our body for building bones and teeth (calcium and phosphorus), formation of blood (iron), coagulation of blood and functioning of muscles (calcium) and functioning of thyroid gland (iron).

The complete filled table is

Tasty food is not always nutritious and nutritious food may not always be tasty to eat. Certain examples in favour of the above statement are
(i) Potato chips are tasty to eat but not nutritious as they contain huge amount of fats.
(ii) Green leafy vegetables either boiled or steamed are very nutritious but not good in taste.
(iii) Certain fast foods like pizza, burger, etc., are very good to taste but are not nutritious as they contain huge amount of fat.

Fats can be tested by a simple test:
(i) Take small amounts of all food materials one by one.
(ii) Place them on a clean white paper and rub with mild force.
(iii) Hold the paper towards light.
(iv) A greasy, translucent spot if appears, indicates the food component rich in fats.
Out of all food items, following are fat rich foods: Oil, butter, meat, pizza, poori, groundnuts.

The two sources of animal fats are- Meat and cheese
(i) Meat from different animals like hens, pigs, etc.
(ii) Cheese from milk produced by cones.

Though water does not provide nutrients yet it is an important component of food because it helps
(i) to transport digested food to body cells.
(ii) to absorb nutrients from the food.
(iii) to get rid of waste products from the body.
(iv) to control and regulate the body temperature.

(a) Oil and ghee are the food items rich in fats.
(b) Rice and potato are the food items rich in starch.
(c) Spinach and cabbage are the food items rich in dietary fibre.
(d) Pulses and milk are rich in protein.

The major nutrients in our food are
(i) Carbohydrates       
(ii) Proteins
(iii) Fats
(iv) Vitamins
(v) Minerals
(vi) Water and roughage