Sea of Exercises (Revised Edition) Junior High School Chemistry

Author: Chief Editor: Shen Xinfu
Publisher:
Publishing Date: 2005-03-01
Features:
Fragment: 17. Which of the following statements about catalysts is incorrect?
A. The catalyst itself does not participate in the chemical reaction
B. The mass of the catalyst does not change before and after the reaction
C. The chemical properties of the catalyst remain unchanged before and after the reaction
D. The catalyst is manganese dioxide
18. Which of the following statements is incorrect?
A. When potassium chlorate is used to produce oxygen, manganese dioxide must be added, otherwise the reaction cannot occur
B. When potassium permanganate is used to produce oxygen, a catalyst is not needed
C. When collecting oxygen in the laboratory using the water displacement method, the tube should be removed from the water first, then the alcohol lamp should be removed
D. The heated test tube should be placed in the outer flame of the alcohol lamp
19. Which of the following statements about oxygen is incorrect?
A. Oxygen is a gas with relatively active chemical properties
B. It can react with all substances
C. Heat is generally released in oxidation reactions
D. Reactions between substances and oxygen always release light and heat
20. The essential characteristic of a chemical change is:
A. Emission of light and heat
B. Formation of precipitation or gas
C. Color change
D. Formation of new substances
21. Which of the following substances is a pure substance?
A. Liquid air
B. Sugar solution
C. Liquid carbon dioxide
D. Residue after potassium permanganate is used to produce oxygen
22. Which of the following substances is a compound?
A. Hydrochloric acid
B. Lime water
C. Liquid oxygen
D. Potassium permanganate
23. Which of the following substances is an oxide?
A. Water
B. Potassium chlorate
C. Sulfuric acid
D. Ammonia
24. Which of the following instruments cannot be used for heating?
A. Beaker
B. Test tube
C. Gas collection bottle
D. Evaporating dish
25. Which of the following is incorrect when using a laboratory balance?
A. Before weighing, the rider is placed at zero, and the balance is checked to see if it reaches equilibrium
B. The left pan of the balance is placed with the substance being weighed, and the right pan is placed with the weights
C. Weights should be used with tongs
D. When weighing, first add smaller weights, then add larger weights until the balance reaches equilibrium
26. The products of the thermal decomposition of basic copper carbonate are:
A. Base, carbonic acid, and copper
B. Copper oxide, water, and carbon dioxide
C. Copper hydroxide, water, and carbon dioxide
D. Copper, carbonic acid, and carbon dioxide
27. In a chemical change, substances must always have:
A. Color change
B. Gas formation
C. Emission of light and heat
D. Formation of new substances
28. Which of the following properties of oxygen does not belong to its physical properties?
A. Oxygen is not easily soluble in water
B. Under normal conditions, oxygen is colorless and odorless
C. Oxygen is slightly heavier than air
D. Oxygen can support combustion
29. Among the following phenomena: ① burning of a stick ② breaking of glass ③ melting of paraffin ④ lighting of a light bulb ⑤ spoilage of food, which belongs to a chemical change?
A. ①④⑤
B. Only ①
C. Only ⑤
D. ①⑤
30. Which of the following gases can cause air pollution?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Sulfur dioxide
31. Which of the following gases can make limewater cloudy?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Carbon monoxide
32. Which of the following changes is not a combination reaction?
A. Burning of charcoal in air
B. Burning of sulfur in oxygen
C. Burning of red phosphorus in air
D. Burning of candle in air
33. Which of the following changes is not a decomposition reaction?
A. Producing oxygen from potassium permanganate
B. Producing oxygen from air
C. Producing oxygen from a mixture of potassium chlorate and manganese dioxide
D. Producing oxygen by electrolyzing water
34. Since the ignition point of white phosphorus is only 40°C, white phosphorus should be stored in:
A. A refrigerator
B. Cold water
C. Kerosene
D. A beaker
35. Which of the following changes is not an oxidation reaction?
A. Respiration of animals and plants
B. Spoilage of food
C. Burning of candle
D. Carbon dioxide making limewater cloudy
36. Which of the following statements is incorrect?
A. Combustion is a vigorous oxidation reaction
B. Oxidation reactions generally release heat
C. Spontaneous combustion is a "fire from heaven" that humans cannot control
D. Any substance produces flames when it burns
37. Which of the following laboratory oxygen production operations is incorrect?
A. Potassium chlorate and manganese dioxide should be mixed in a 3:1 mass ratio for uniformity
B. The test tube containing the reagent should be fixed on the iron stand, and the mouth of the test tube should be slightly inclined downward
C. The collected oxygen can be collected using the water displacement method
D. When the oxygen is full in the gas collection bottle, the alcohol lamp should be extinguished quickly
38. Which of the following statements is correct?
A. Burning of a candle in oxygen is a combination reaction
B. Producing oxygen from potassium chlorate is a decomposition reaction
C. Spontaneous combustion is caused by the slow oxidation of substances
D. As long as the temperature reaches a certain point, any substance can burn in oxygen
39. Under certain conditions, substances that burn violently in oxygen and produce sparks are:
A. Hydrogen
B. Charcoal
C. Iron wire
D. Sulfur
40. The correct statement about catalysts is:
A. Using a catalyst can increase the amount of product
B. Adding a catalyst always speeds up the reaction rate
C. Without a catalyst, substances cannot undergo a chemical reaction
D. Using a catalyst can change the reaction rate of substances
【True or False Questions】
41. Any change that emits light and heat is a chemical change.
42. Reactions between substances and oxygen are all combination reactions.
43. Physical changes can be used to separate the components of air, indicating that air is a mixture.
44. To prevent the filtrate from splashing, the lower end of the funnel should be close to the bottom of the beaker.
45. When the alcohol lamp is not in use, it should be extinguished immediately with the mouth to avoid waste.
46. Solid reagents should be taken with a spatula, and some lumped reagents can also be taken with tongs.
47. The physiological saline used for injections is a pure substance.
48. Pure substances have fixed properties.
49. A laboratory balance can accurately measure 25.25 grams of potassium nitrate.
50. If concentrated sulfuric acid accidentally gets on the skin, it should be rinsed off immediately with water.
51. When measuring the volume of a liquid with a graduated cylinder, if the eye level is higher than the concave meniscus, the reading will be larger.
52. In the experiment to purify coarse salt, the filtrate should be completely evaporated in an evaporating dish and then heating should be stopped.
53. If a burning stick is inserted into a gas collection bottle and the stick goes out, the gas collection bottle must contain nitrogen.
54. If alcohol spills and catches fire on the desk, it should be immediately covered with a wet cloth.
55. Substances that cannot burn in air will also not burn in oxygen.
56. The main components of air are nitrogen and oxygen, and it also contains a small amount of rare gases, carbon dioxide, and water vapor.
57. If all the dissolved gases in natural water are collected and analyzed, the result is: oxygen accounts for more than 21% by volume, while nitrogen accounts for less than 78% by volume, indicating that nitrogen is more difficult to dissolve in water than oxygen.
58. When white phosphorus burns in oxygen, it produces white smoke and forms phosphorus pentoxide.
59. Oxygen is not easily soluble in water, so oxygen can be collected using the water displacement method.
60. Separating oxygen and nitrogen from liquid air is based on the fact that liquid oxygen is denser than liquid nitrogen.
【Fill-in-the-Blanks】
61. The gas with the highest content in the air is ① gas. Under normal conditions, it 【Short Answer Questions】
71. Why must a small amount of white phosphorus be stored in cold water?
72. How can three gas collection bottles containing oxygen, nitrogen, and carbon dioxide be distinguished using a simple method?
73. What are the differences and connections between combustion and slow oxidation?
74. Why does a candle flame go out when fanned, while a coal furnace fire becomes stronger when fanned?