Ключевые слова: acid, alkaline, analyzing, angle, background, biochemistry, biology, biotechnology, care, chart, chemical, chemist, chemistry, closeup, colors, comparison, control, diagnostic, equipment, examining, experiment, expertise, graph, health, horizontal, instrument, isolated, isometric, laboratory, litmus, measurement, measuring, medical, medicine, paper, ph, reagents, research, sample, science, scientific, stick, strip, swatch, technology, test, tool, variation, water, yellow,