Across 2. mass divided by density (volume) 7. 10^3 (kilo) 8. you can see though the glass, because it is ... (transperent) 9. microscopic particle of matter the size and weight, the smallest part of a chemical element, which is the carrier of its properties (atom) 13. the image in mirror can be real or .... (virtual) 16. F*l (work) 19. it is equal to 1000 metrs (kilometer) 21. the sum of the angles is 180 degrees (triangle) 23. increase (magnification) 25. 10^-9 (nano) 26. word 'ray' in plular (beam) 29. process that occurs without a change in pressure (isobar) 30. 10^-12 (piko)