Urgently, ask for a few chemistry problems, and if you can solve them, please enter

1: 1) Sodium chloride, sodium hydroxide, sodium carbonate.

2) Sodium carbonate solution reacts with dilute hydrochloric acid to generate sodium chloride, carbon dioxide and water, when there are no more bubbles, after adding calcium hydroxide solution, white precipitate appears, indicating that dilute hydrochloric acid is insufficient, and sodium carbonate is left; The remaining sodium carbonate solution reacts completely with the added calcium hydroxide solution to form sodium hydroxide and calcium carbonate precipitates. The solutes contained in the solution at this time are sodium chloride and sodium hydroxide.

Method 1. A small amount of supernatant is taken into a test tube, and carbon dioxide gas is introduced into the supernatant.

There is a white precipitate generated.

Method two. Take a small amount of supernatant solution in a test tube, and add sodium carbonate solution to the supernatant.

There is a white precipitate generated.

Two: I have a dispute about this question, he said: smelting pig iron with hematite containing 80% iron, the problem is here, if the question is the ore containing 80% Fe then it is solved by your method, but I thought at first, (generally I also think so, if it is Fe80% then this question is too simple) said to smelt iron ore containing 80% hematite, I also do it according to this understanding.

Solution: Suppose the mass of hematite is x tons.

fe2o3 --2fe

x*80% 1120*95%

x=1900t

Three: Solution: Let the mass of NaOH be X, then:

2naoh+h2so4=na2so4+2h2ox 100kg*

Solution x = 4kg

Let the quality of Ca(OH)2 be y.

ca（oh）2+h2so4=caso4+2h2oy 100kg*

Solution: y = In the past, NaOH was consumed 4kg of NaOH per 100kg of product (the result of the first question), but now with Ca(OH)2, every 100kg of product is consumed, and sodium hydroxide is 24 yuan per kilogram of sodium hydroxide, and calcium hydroxide is 6 yuan per kilogram.

You can save money: 4 times 24 - multiplied by 6 = yuan.

I say this, you can get the idea.

Four: I didn't do it without a picture.,I didn't understand what you described.,Forgive me for being ignorant.,Mathematics and Chinese knowledge can't learn well.,I just can't understand what you're described.,I'm sorry.。。。

Conjecture 3: sodium chloride, sodium hydroxide, sodium carbonate.

The reason for conjecture 1 is that the remaining sodium carbonate reacts exactly 1 to 1 with calcium hydroxide.

When there is an excess of aluminum and magnesium, choose D

In this case, as long as two substances of equal mass are added, hydrogen of the same mass can be released, and the increased mass is the same.

When there is an excess of acid, choose C

In this case, al:h2=9:1 (according to the equation) and mg:h2=12:1 (the same reason) is the answer.