1) elements of d-block are arranged in........groups, and ........clumens  a) 8,10 b) 4,9 c) 6,5 d) 10,8 2) the halogen,which can be prepared artificially is...... a) iodine b) bromine c) astatine d) chlorine 3) .......rays are used in preservation of food a) beta b) UV c) gamma d) laser 4) the boiling point of liquefied nitrogen is............ a) 0 b) 100 c) 196 d) -196 5) ..water pollution causes the death of marine creatures due to the separation of the dissolved oxygen from water a) radiant b) chemical c) thermal d) biological 6) increasing the concentration of.... in drinking water causes cancer a) lead b) arsenic c) mercury d) chlorine 7) what is the percentage of erosion of ozone layer in an area,if you know that the degree of its ozone is 150 dobson a) 50% b) 30% c) 40% d) 150% 8) what is the wave length of the near ultraviolet rays a) 280:315 b) 100:280 c) 315:400 d) 215:400 9) the normal atmospheric pressure........... a) 1013.25 b) 76 c) 1.013 d) 760 10) ammonites fossils are found in the limestone rocks of el-mokattam mountain a) true b) false 11) mosses and ferns appeared after a) gymnospern b) angiosperns c) algae d) amphibians 12) from green house gases a) oxygen b) nitrogen oxide c) nitrous oxide d) sodium oxide 13) the movement of air is vertical in a) stratosphere b) mesosphere c) troposphere 14) non-metalic property of the same period.......by increasing the atomic number a) increase b) decreases c) does not change 15) the number of known elements is.......... a) 300 b) 119 c) 100 d) 118

science grade 8

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