Grade 8 (Grade 2) Physics Reference Answers and Grading Opinions
1. Can you choose the correct answer? (***29 points, 1-7 has only one correct option for each question, 3 points for each small question, and fill in the serial number of the option you think is correct in the space. Questions 8 and 9 are multiple-choice questions, and each question has two or more correct options. 4 points for each small question, 2 points for choosing the right one but not all; Wrong choice, no choice, 0)
1.A 2。 C 3。 C 4 explosive B 5。 D 6。 C 7。 D 8。 BCD 9。 ab blood type
Can you fill in the blanks with what you have learned (***2 1, 1)?
10. Xiao Lv
The glass ball of the thermometer hit the bottom of the cup.
12. Left 6.35×10-22×10-53.175×103kg/m3.
13. Reasonable
14. Post reduction
15. The liquid temperature is reasonable (pay attention to control variables).
16. Front concave lens
17. Reasonable
18. Reasonable
19. It is reasonable to put forward that water resources are polluted and people use water excessively.
3. Can you make the following pictures correctly and answer the following questions? (** 16, item 20, item 2, item 2/kloc-0, item 5, item 22, item 23, item 4,)
20. Draw the normal line 1 correctly and draw the incident light 1 correctly.
2 1. Position, size and arrow direction are correct 1 min, projector and slide projector 1 min (other answers are reasonable).
22.( 1)① When using, the measured object can be left for reading; (2) Throw it after use (refer to the score for other reasonable answers) 1 minute.
(36.5A Principle that a convex lens can form an upright magnified virtual image (per space 1 point)
23.40cm3 40cm3 in the table is the total volume of copper block 3 and water (other reasonable answer reference score) (1 minute per grid).
4. Can you complete the following experiments and explorations? (**25 points, item 24 8 points, item 25 5 points, item 26 8 points, item 27 4 points)
24.( 1) The incident light and refracted light are given correctly 1.
(2) The center of the light screen is not at the same height as the optical center of the convex lens and the flame center of the candle flame; Moving the light screen downwards so that the center of the light screen is at the same height as the optical center of the convex lens and the flame center of the candle flame; (If other answers are reasonable, you can give points, each space 1 point)
(3) observing the candle image through the convex lens; Left; Fall head; Small (1 point/space)
(4) Double focal length (1 point)
25.( 1) Thermometer (1)
(2)B； Reasonable enough; (65438+ 0 point per grid)
(3) unchanged; Decrease (per space 1 dot)
26.( 1) If the experimental record is in a reasonable form, you can score 3 points.
(2) The measuring cylinder is easy to dump on the balance, and it is difficult to measure its mass; (1) The liquid in the beaker is not clean, resulting in a smaller measured liquid volume (1).
(3) ① Pour a proper amount of liquor into a beaker, and measure the total mass of the beaker and liquor with a balance (1); ② Pour part of the liquid into the measuring cylinder, and then measure the total mass of the remaining liquid and beaker with a balance (1); ③ Measure the volume of liquid in the measuring cylinder. (1 min) (other methods can be scored reasonably)
27. Liquefaction; (1) Ninghua; (1) The temperature at the spout is close to the temperature of the water vapor ejected from the spout. The water vapor lacks liquefaction conditions and cannot be liquefied into small water droplets, forming a "cloud", so it cannot "rain". (2 points) (If other explanations are reasonable, points can be added)
5. Can you complete the following calculations? (9 points)
28. Kg/m3; Temperature; (65438+ 0 point per grid)
It is suggested that the maximum daily intake of melamine is equal to its own mass × 0.32mg/kg (3 points for correct calculation).
Maximum daily intake volume of melamine = maximum daily intake mass of melamine ÷ melamine density (give 4 points for correct calculation).