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A: Select BAnalysis: From the meaning of the title, the mass of calcium sulfate crystals is: , the mass of calcium sulfate is: =, CaSO4·XH2O =δ= CaSO4 + XH2O

136+18x~~~136

The column proportional solution yields: x=2

Hence BGood luck with your studies!

The quality of calcium sulfate crystals is, of which calcium sulfate has.

Set to caso4·xh2o

Then there is 136:(136+18x)=:

So x=2 and the answer is b

Calcium sulfate weighs the amount of its substance.

Water weighs the amount of its substance.

Calcium sulfate: water = 1:2 choose b

Optional) (136+18x)=

Solution: x 2

Among them, the molecular weight of CaSO4+XH2O is 136+18X

Analysis: The mass of calcium sulfate is:

The mass of the crystalline water is:

CaSO4·XH2O=== (Condition: Heating) CASO4+XH2O136 18X

Column equation: 136

Solution: x=2 to choose b

NA is burned in the air to form superoxide.

2na+02→na2o2

na2o2+2h20→2naoh

h2o22h2o2→2h2o

22 parts of Na O1 part hydrogen peroxide.

Produce parts of oxygen.

So the molar ratio of sodium to oxygen is 4 to 1

Na is moles and oxygen is moles.

Oxygen mass is.

Multiply by 32 = grams.

Solution: Equation of the interaction between sodium and water:

2na＋2h2o＝2naoh＋h2↑

The amount of substance of Na is:

mol so the hydrogen gas generated is:

mol=g sodium is burned in the air to form sodium peroxide.

2na+02=na2o2

Sodium peroxide reacts with water to produce sodium hydroxide and hydrogen gas.

na2o2+2h20=2naoh

The total response of the two responses to the O2 appeal was:

2na+02+2h20=2naoh

O2 Na is, so oxygen is.

Therefore, the mass of oxygen produced is .

The relative molecular mass of a is 28*2=56, and that of b is 28And A and B contain 86% carbon.

Then the chemical formula A is C4H8 and B is C2H4.

The carbon tetrachloride solution that can discolor bromine is presumed to be an olefin. So a is butylene and b is ethylene. where a has isomers.

Ach3CH2CH=CH2, CH3CH=CH3, CH3C=CH2 are the three isomers.

CH3CH2 = CH2 +BR2 = CH2BR-CH2BR (1,2-dibromoethane).

The relative density of carbon n(c):n(h)=1:2 hydrocarbon a hydrogen is 28 m (hydrocarbon a) = 56g mol The amount of hydrocarbon b formula is half that of a m (hydrocarbon b) = 28g mol hydrocarbons can discolor the carbon tetrachloride solution of bromine Both hydrocarbons contain carbon-carbon double bonds 1

In summary, it can be seen that there are two isomers in hydrocarbon A is C4H8 (butene) and hydrocarbon B is C2H4 (ethylene).

Positional isomerism: CH2=CH2CH3(1-butene), CH3CH=CH3(2-butene).

Carbon chain isomerism: (CH3)2C = CH2 (methacrylene) + BR2CH2BR2BR

86 12:14 1 1:2, it can be seen that the experimental formula of A and B are both CH2, and it is known that both can fade bromine water, and both are olefins.

According to the relative density of hydrogen, the relative molecular weight is known to be , and then according to the CH2 formula of 14, A is butene C4H8 and B is ethylene C2H4.

There is no isomerism in ethylene, but butene does, CH3-CH2-CH=CH2 (1-butene), CH3-CH=CH-CH3 (2-butene), (CH3)2C = CH2 (methapropylene).

ch2=ch2 + br2 → ch2brch2br。