Sodium nitrate, 5 M: Dissolve 42.5 g of reagent-grade material in 100 ml of water. Chloride standards for calibration of the ion-selective electrode meter: − Stock solution (1000 mg/l): Transfer 1.650 g of reagent grade sodium chloride to a 1-litre volumetric flask. Add ca. 500 ml ...
Access to safe drinking-water is important as a health and development issue at national, regional and local levels. In some regions, it has been shown that investments in water supply and sanitation can yield a net economic benefit, as the reductions in adverse health effects and health-...
根据第三段中"Sunlight acts as a catalyst for a process that turns the nitrogen oxides into water,small amounts of CO2 and calcium nitrate(在将氮氧化物转化为水、少量二氧化碳和硝酸钙的过程中,阳光充当了催化剂)"可知,在这个过程中,阳光的作用必不可少。故选A。(3)A.观点态度题。根据...
WHO/SDE/WSH/03.04/04 English only Chromium in Drinking-water Background document for development of WHO Guidelines for Drinking-water Quality ___ Originally published in Guidelines for drinking-water quality, 2nd ed. Vol. 2. Health criteria and other supporting information. World Health Organization...