Science Revision Worksheet Year 8

Transcription

1 Science Revision Worksheet Year 8 Name : Class 1. Complete the table Date Compound Molecule No. of elements No. of atoms Formula Chemical name Water H 2 O SO 2 NH 3 Methane 2. Fill in the missing words in these word equations a) +oxygen Carbon Dioxide b) lead + oxygen oxide c) Copper + oxygen copper d) Tin + tin chloride e) Sodium + chlorine

2 3. Give word equations for reaction of magnesium with a) hydrochloric acid b) sulphuric acid c) nitric acid 4. Find all the elements in the text below and circle them. Underline all the compounds. Draw boxes around the mixtures. a) Rust is formed when iron objects are left out in the air. The iron reacts with the oxygen in the air to form iron oxide (rust). Rust can be turned back into iron by mixing it with carbon and heating it to a high temperature. b) There are a number of different gases in the air. The main ones are nitrogen and oxygen, but there are also small amounts of argon, carbon dioxide and water vapour. 5. Which arrow shows the reflection of light ray X? Give reason for your choice.

3 6. Sunita puts on a pair of special glasses as shown below. The glasses have coloured filters in them. a) Sunita looks at a lamp through the green filter. The lamp gives out white light, but appears to be green. Explain how this is possible. b) Sunita looks at a red lamp. What colour will the lamp appear to Sunita, if she looks at it through the green filter? Explain your answer. 7. Fill in the sentences using the words which describes a process a) White light is made up of different colours. b) You can split up white light using a c) When white light passes through a prism the different colours are d) This process is called 8. Calculate the pressure if a force of 24N is applied on an area of 10 m 2

4 9. A box has the dimensions of 50 cm x 30 cm x 15 cm, weighs 150 N, and is to be placed on a fragile surface. The surface can only withstand a pressure of 0.25 N/cm 2. Which faces of the box can be placed on the table? a) Area of side A: b) Area of side B: c) Area of side C: d) Pressure exerted when side A is placed on the surface: e) Pressure exerted when side B is placed on the surface: f) Pressure exerted when side C is placed on the surface: g) Which face/s of the box can be placed on the fragile surface? h) How did you reach your conclusion? c a b i) How can you explain why this is the case? 10. Write the Photosynthesis Equation Which of these metals is the most reactive with acid? Arrange them in the order of their reactivity. Write 1, 2, 3, or 4 accordingly. a) Aluminium b) Iron c) Copper d) Zinc

5 12. Look at the nutritional information label and answer the questions. Bread NUTRITIONAL INFORMATION per 100 g energy protein carbohydrate fat fibre sodiium 920 kj 5.6 g 58.4 g 12.5 g 22.5 g 80mg a) How much protein is in 100 g of bread? b) Which food substance does bread contain the most of? c) Does it contain more protein or mineral? How do you know? d) Give word equations for digestion of starch, protein and fats. 13. Air contains a mixture of gases. a) What would you use to test a gas to see if it were carbon dioxide and what would you see happening? b) Give another test for carbon dioxide.

6 c) Cigarette smoke contains many substances which are harmful to the body. What is the effect of carbon mono oxide on the body of an athlete? d) List the many different ways of carbon mono oxide entering the body 14. Describe the process of formation of igneous, metamorphic and sedimentary rocks. 15. Compare the following: a) Photosynthesis and respiration b) Respiration and burning c) Models of solar system by Ptolemy, Copernicus and Kepler d) Insect pollinated and wind pollinated flower.

7 16. Figure 8 shows the effect of running on the rate of blood flow through the athlete s muscles a) i For how many minutes did the athlete run? Time = minutes ii Describe what happens to the rate of blood flow through the athlete s muscles during the run. Use data from Figure 8 in your answer..

8 17 Three pairs of chemicals are listed below. A reaction only takes place with two of the pairs. Draw a line from each reaction to the correct result. Draw only three lines.