Answer:
1 = strontium
2 = technetium
3 = silver
Explanation:
Strontium is present in 2 group of periodic table. It is alkaline earth metal. It is most reactive element and can not found free in nature. it is insoluble in water but react with water and form strontium hydroxide and hydrogen gas is also produced. It is radioactive element.
It is similar to the calcium and can incorporated into bones. The food rich with strontium is used to avoid the osteoporosis. It is found in leafy vegetables, grains, sea foods etc.
In given series strontium is highest in reactivity then technetium, while the technetium is more reactive than silver. The silver is less reactive as compared to both given elements.
Answer: B.They are arranged in energy levels
Explanation: Electrons orbit around the nucleus of an atom, and are not spread around equally throughout an atom because there are a different amount of electrons that can fit in each energy level or electron shell (both are the same thing). For example the first energy level can hold up to 2 electrons, the second shell can hold up to 8 electrons, the third can hold up to 18, and so on represented by the equation 2(n^2)
Explanation:
Matter can be classified into two broad categories: pure substances and mixtures. ... A material composed of two or more substances is a mixture. Elements and compounds are both examples of pure substances. A substance that cannot be broken down into chemically simpler components is an elementOne useful way of organizing our understanding of matter is to think of a hierarchy that extends down from the most general and complex to the simplest and most fundamental (Figure 3.4.1 ). Matter can be classified into two broad categories: pure substances and mixtures. A pure substance is a form of matter that has a constant composition (meaning that it is the same everywhere) and properties that are constant throughout the sample (meaning that there is only one set of properties such as melting point, color, boiling point, etc. throughout the matter). A material composed of two or more substances is a mixture. Elements and compounds are both examples of pure substances. A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A substance that can be broken down into chemically simpler components (because it has more than one element) is a compound. For example, water is a compound composed of the elements hydrogen and oxygen. Today, there are about 118 elements in the known universe. In contrast, scientists have identified tens of millions of different compounds to date.
Answer:
The molar mass of MgCI2 is 95.211 g/mol
