Topic content:
Using the chemical knowledge learned, complete the following:
(1) In order to prevent the photo from fading, the photo can be laminated (sealed with plastic film) for isolation;
(2) In order to make steamed bread, bread and other hair noodles loose, porous, soft and delicious, __________ is often added;
(3) There are ① cucumbers ② tofu ③ steamed buns ④ eggs, among which protein is rich (fill in the number)
(4) Clothes made of pure cotton are preferred. The available methods for identifying pure cotton and polyester;
(5) Lack of essential trace elements in human body will lead to diseases, such as goiter (commonly known as big neck disease);
(6) Crop growth has certain requirements on soil pH, and soil pH is usually measured.
(7) The fire extinguishing method available when the oil pan catches fire is
Best answer:
(1) Oxygen (or air) (2) baking soda (or soda ash) (3) ② ④ (4) combustion
(5) Iodine (6) pH test paper (7) Cover the pot (or put cold dishes)
Answer analysis:
(1) In order to prevent the photo from fading, the photo can be laminated (sealed with plastic film) to isolate oxygen and water
(2) Sodium bicarbonate is the most widely used loosening agent in the food industry
(3) Tofu and eggs are rich in protein
(4) Pure cotton is a natural fiber and polyester is a synthetic fiber. When burning, the phenomenon and smell are obviously different, and polyester will generate a pungent smell.
(5) Lack of certain trace elements in human body will cause diseases, and lack of trace element iodine will cause goiter
(6) Crop growth has certain requirements on soil pH, and pH test paper is often used to measure soil pH
(7) If the cooking oil in the frying pan catches fire, you can use the method to isolate the air: cover the pan to extinguish the fire
Test core:
The existence form of elements in human body:
① Carbon, hydrogen, oxygen and nitrogen mainly exist in the form of water, sugar, protein, vitamins and fat.
② Other elements mainly exist in aqueous solution in the form of inorganic salts.
③ Calcium element mainly exists in the form of hydroxycalcium phosphate [Ca10 (PO4) 6 (OH) 2] crystal.