That benevolent brother sent me a few chemistry questions for junior high school chemistry Please!

There is a bottle of dilute salt water in the laboratory, which is sealed and preserved, and the following statement is correct that ( ) a lower salt water is saltier.

b The upper part of the salt water is saltier.

c The upper and lower parts of the salt water are as salty.

d There is a certain amount of salt solids at the bottom of the bottle.

CF is the most common metal, so it is iron and copper, B is the lightest gas, so it is hydrogen, D is a light green solution, so it is a ferrous solution, G is a blue solution, so it is a copper ion solution can be considered as copper sulfate, C + G generates D and F, so C is iron, A is an oxide of iron, which is generated by the ignition of iron and oxygen, and is ferric oxide.

cuso4 == feso4 +cu

4Co = High temperature = = 3Fe +4CO2 + H2SO4 = FeSo4 + H2 (gas symbol) look. Feel free to ask.

B: K2CO3 + H2SO4 = K2SO4 + CO2 +H2OK2CO3 + 2HNO3 = 2KNO3 + CO2 +H2OBaCl2 + H2SO4 = BASO4 +2HClBACl2+K2CO3=BAC3 +2KCL According to the precipitation and gas, each reagent can be analyzed.

D: First of all, from the color, you can tell that the yellow solution is FeCl3. FeCl3 was added to the other 3 respectively, NaOH was precipitated, and NaOH was added to the other 2 respectively, MgCl2 was white precipitated, and BaCl2 was not precipitated

B: BaSO4 is an acid-insoluble precipitate, while BaCO3 is acid-soluble.

D: FeCl3 yellow solution, judging from the color first, in the addition of the other 3, the precipitate is NaOH, the NaOH is identified, in the addition of the remaining 2, the white precipitate is MgCl2, and the last is BaCl2

Because there are two carbon atoms and one oxygen atom in a dimethyl ether molecule; So 1 mole of dimethyl ether has 2 moles of c atom and 1 mole of o atom.

The relative molecular mass of dimethyl ether is 46, so we know that its mass is calculated by dividing its molar mass by the relative molecular mass, and the answer is 10 moles The total molecule is multiplied by the number of moles multiplied by the number of molecules in one mole (multiplied by 10 equals.

You don't know what you're going to ask before and after your first question, so be clear.

Dimethyl ether "Chemical Formula: (C2H6O)".

The 1 mol dimethyl ether molecule has --- 2---mol carbon atom ,-- 1---mol oxygen atom.

The amount of 460g of dimethyl ether is ---10---mol, which contains a dimethyl ether molecule.

Second, it is not clear what is being said.

Dimethyl ether molecular formula CH3-0-CH3 ether general formula r -0-r2mol 1mol

10mol 10na=pcs.

CaCO3 has a relative molecular mass of 100 Ca, and the relative atomic mass of Ca is 40, so it is 40 100 = 40%.

Therefore, it is 1 gram (this is CaCO3, there is a trace of vitamin D in calcium tablets, about a few hundred micrograms, which can be ignored).

2 mol carbon atom, 1 mol oxygen atom.

10mol, multiplied by 10 to the 24th power.