The following groups of substances are not only accurate in their property comparisons

The greater the non-metallic property, the stronger the oxidation, and the stronger the hydrogen bond formed by its hydride, so H2S>PH3 >SiH4

Answer]: Melting point: Since sulfur dioxide is a high bridge-resistant molecular crystal with the lowest melting point, and calcium oxide and magnesium oxide are ionic crystals, the charge of calcium and magnesium ions per mu is the same, but the radius of calcium ions is greater than that of magnesium ions, so the enthalpy of calcium oxide lattice is less than that of magnesium oxide, and the melting point of magnesium oxide is higher than that of calcium oxide, so the order of their melting points from high to low is mgo, cao, so2

Due to bacl2

It is a typical ionic crystal, so the melting point is the highest, while Ccl4

It is a molecular crystal with the lowest melting point, while aluminum chloride and ferric chloride already have some covalent molecular crystals. The melting point of the molecular crystal increases with the increase of the relative molecular mass, and the relative molecular weight of ferric chloride is larger than that of aluminum chloride, so the melting point of ferric chloride is higher than that of aluminum chloride, so the order of melting point from low to high is: CCL4

alcl3fecl3

BaCl2 has the highest melting point because SiC is an atomic crystal, whereas KCl is an ionic crystal with a higher melting point. sncl4

and alcl3

It has partially covalent crystals, while SNCL4

than alcl3

The relative molecular mass is large, and the same reason as above, SNCL4

than alcl3

The melting point is high, so the order of the melting point from low to high is: AlCl3

sncl4kcl，sic。$Hardness: SiO2

atomic crystals) mno2

ionic crystals) CO2

molecular crystals). $Solubility: Zn, cd, and Hg both belong to the second subgroup, and are all 18-electron shell configurations, with large polarization force and deformation, and the larger the radius, the greater the deformation, and they are the same as the easily deformable S2-

With the increase of the radius of Zn, Cd and Hg, the mutual polarization is enhanced, so the covalentity of the sulfides formed increases in turn, and the solubility decreases in turn, so the solubility of Zns cds hgs. $Thermal stability: Thermal stability of alloacids and their salts:

The acid is smaller than the acid salt, the acid salt is smaller than the positive salt, the positive salt charge is the same, and with the increase of the positive ion radius, the reverse polarization of the ion is small, and the thermal stability of the positive ion increases, so h2

co3mg(hco3

mgco3baco3

Answer D Question Analysis: The physical properties of a substance refer to the properties that do not need to be expressed by chemical changes, such as color, state, odor, density, melting point, boiling point, etc. The chemical properties of a substance refer to the properties that are manifested through chemical changes, for example, stability, oxidation, reduction, toxicity, flammability, etc.

Take advantage of the different tastes of salt and sugar, you can separate the two; Taking advantage of the different colors of copper and aluminum, you can separate purple-red copper from silvery-white aluminum; Gasoline and alcohol, alcohol is easily soluble in water and gasoline is insoluble, and the separation of the two can be realized; The physical properties of clarified lime water and water are basically the same, and there is no obvious difference. The distinction should be made using chemical properties.

Test Center: This question examines the difference between chemical and physical properties and their applications.

Comments: Physical properties and chemical properties are the most basic concepts of junior high school chemistry, and they are one of the hot spots in the examination.

Answer] C Answer Analysis] Question Analysis: Option A, False. For the same period element, from left to right, the first ionization energy gradually increases the tendency, but in some special cases, because the electrons in the filled and semi-filled states in the Hunt rule are more stable, the first ionization energy mg option, is wrong.

In atomic crystals formed by covalent bonds, the smaller the atomic radius, the shorter the bond length, the greater the bond energy, and the higher the melting and boiling points of the crystal. Such as melting point: diamond, silicon carbide, crystalline silicon.

Option c is correct. d option, false. Test Center:

a. Because both carbon and hydrogen can reduce the oxides of some metals, they both reflect the reducibility, that is, the chemical properties are similar, so A is wrong;

B. Because dilute hydrochloric acid and dilute sulfuric acid produce a large number of cations in water, all of which are hydrogen ions, which have the same nature as acids and similar chemical properties, so B is wrong;

c. The anions produced by calcium hydroxide and sodium hydroxide in water are all hydroxide ions, which have the same properties as alkalis and similar chemical properties, so C is wrong;

d. Because carbon monoxide is reducible and carbon dioxide is oxidizing, their chemical properties are not similar, so D is correct;

Therefore, d

1.Oxygen is pure, air is a mixture.

2.Carbon dioxide does not support combustion, and carbon monoxide can.

3.When carbon dioxide is flushed in, there is no obvious phenomenon in the former, and white precipitation appears in the latter.

CO2 (only it is a non-metal oxide).

Cu (only it is metal).

O2 (only it is a non-metal).

H2O (only it is oxide).

Basic copper carbonate Cu2(OH)2CO3

2 cu + o2 + co2 + h2o = cu2(oh)2co3