百度试题 结果1 题目The discovery of new elements ___ important for the development of chemistry. A. is B. was C. are D. were 相关知识点: 试题来源: 解析 A。讲述的是客观事实,用一般现在时,“discovery”是单数,所以用“is”。反馈 收藏 ...
The naturally occurring elements that are present in high abundance, determine the nature of the environment as a whole through the properties, or behavior of themselves or their compounds. This chapter describes the chemistry of some of the most important elements that is related to the properties...
concentrated sulfuric acid water after precipitation with vitriol 4. it is only active metallic elements or active nonmetallic elements that can react with cold water to emit gaseous substance For example, 2Na2O2+2H2O error, O2 = +4NaOH 5. liquefied air, and then gradually warming, the first ...
What is the importance of chemistry in everyday life? Why is stoichiometry important? What is the importance of chemistry in geology? Why are chemical elements important? Why is biological oceanography important? How does mass spectrometry work in forensic toxicology?
The concentrations of the elements in the annual rings of Pinus massoniana reflect the influence of both regional factors and species characteristics in absorbing,accumulating and distributing elements.The changes of environmental factors may result in concentration changes of elements in tree rings.Therefor...
We create empirical formulas by dividing the number of atoms in a molecular formula by their greatest common denominator, the largest possible number that is a factor for all the numbers in the formula. This shows us the ratio of the atoms but it is not considered a true formula because it...
It's the eighth most abundant element in the observable Universe, but the third most abundant on Earth. As a little scientific bonus, all this silicon indicates that Earth and the other rocky planets formed toward the center of the nascent Sun's accretion disc, where heavier elements ...
In this paper, we present the distribution of some microelements in fresh leafy vegetables: dill, parsley, celery, lettuce, and spinach. Experimental results obtained through atomic absorption spectrometry show that vegetable leaves contain important amounts of essential microelements: Fe, Mn, Zn, Cu...
Why is hydrogen important in our bodies? Why is it important that ice is less dense than water in biology? Why is the water table important? Why is the water cycle important? Why are chemical elements important? Why is water such a good solvent?
What is the importance of chemistry in geology? Why are chemical elements important? Why are minerals important to the rock cycle? Why is chemical analysis important? Why is the oxide mineral group important? Why are basalt and granite important igneous rocks?