There are a few science questions that I really can t do, so help if you can do them! 20

Bananas are the most perishable when put together with a, bananas.

I've tried it at home, and it's all like this, bananas and bananas are put together, and they are more likely to rot than pears and apples.

c. Magnolia flowers do not sprout first and then bloom, but bloom first and then germinate.

I have a magnolia tree that blooms first every spring, and when the flowers are gone, the leaves begin to sprout.

AC bananas release something similar to a ripening agent.

a.Hydrochloric acid: 2HCl + Ca(OH)2==CaCl2+2H2O (no color, gas, precipitation in the reaction).

b.Ferric chloride solution: 2FeCl3 + 3Ca(OH)2==2Fe(OH)3 +3CaCl2 (reddish-brown flocculent precipitate appears).

c.Copper sulfate solution: CuSO4 + Ca(OH)2==Cu(OH)2 + CaSO4 (blue flocculent precipitate appears).

d.Phenolphthalein solution: The main component of lime water is calcium hydroxide, which is alkaline, and the phenolphthalein test solution is red when alkaline.

The correct answer should be A

AhCl + Ca(Oh)2 CaCl2 + H2O limestone is originally clear, this reaction does not produce precipitation, and no gas is released to form Fe(Oh)3

c generates Cu(OH)2

dPhenolphthalein discoloration.

Lime water is calcium hydroxide, and the analysis is as follows:

There is no precipitation of gas, that is, there is no obvious phenomenon;

Iron hydroxide is a reddish-brown flocculent precipitate;

Copper hydroxide is a blue precipitate;

d.Lime water is a strong alkali, and phenolphthalein turns red when exposed to alkali.

Only A is eligible

I worked on chemistry for a long time.

Answer: AA: Ca(OH)2+2HCl=CaCl2+2H2O, no obvious phenomenon B: 2FeCl3+3Ca(OH)2=2Fe(OH)3 +3CaCl2, reddish-brown precipitate.

C: CuSO4+Ca(OH)2=Cu(OH)2+CaSO4, blue precipitate.

d: Phenolphthalein turns red when exposed to alkali.

The main component of lime water is calcium hydroxide, which reacts with iron chloride solution to form iron hydroxide precipitation. It is a phenomenon with copper sulfate solution to generate copper hydroxide precipitation. Because calcium hydroxide is alkaline and turns red when phenolphthalein, there is a phenomenon, so choose A

c. Red phosphorus, dark red solid.

It can react with oxygen to form phosphorus pentoxide and consume oxygen.

Because buoyancy is related to the volume of the liquid that is removed, and in the case of exhaustion, it depends on who has the largest volume. And because the mass is the same, the density is high, and the volume is small, so the last is the comparison, which is higher density copper or iron?

3.No change. Because the mass of suspended solids has not changed. So gravity = buoyancy.

4. a5.Same as p (rou).

standard units); 1000 standard units).

Lu; Aluminum*p water;7 p aluminum*ppwater*g

2n, the elongation is 12cm, and it is said that Sakura Hanming 1n elongates Sanqing 1cm

Therefore, under the gravity of 6n, the length of the spring is (16) cm; Under the pressure of 2n, the length of the spring is (8) cm

It elongates 6cm under the pressure of 1n

6x6=46

2x6=22

It elongates 6cm under the pressure of 1n

6x6=46

2x6=22 2n, the elongation is 12cm, which means that 1n is elongated by 1cm, so under the heavy extinction force of 6n, the length of the spring is (16)cm; At a pressure of 2n, the length of the spring is (8) cm

1.Pick B.

a.False, the organic matter produced by photosynthesis constitutes the main part of the plant body;

c False, plants consume light energy during photosynthesis;

D, the energy required for the life activities of plants is provided by respiration.

2.Choose:? (I'll see what other people have to say).

A is wrong, B is wrong, no matter day or noon or night, plants carry out respiration;

cFalse, living plant bodies are respiring all the time;

dFalse, photosynthesis can provide raw materials for respiration, and respiration can provide energy for the synthesis of enzymes and pigments in photosynthesis.

The white solid insoluble a is calcium carbonate; Blue liquid c is copper sulfate; The unchanged d is potassium nitrate; c is barium chloride.

bacl2+2agno3→2agcl+ba(no3)

cubic kilogram locust chong square meter = kilogram cubic decimeter.

Kilogram trouser bridge 5 cubic decimeters = kilograms cubic decimeters" kilograms cubic decimeters.

If it does not meet, it should be added The density of water is 1 kilogram Hu Mingmeng cubic decimeter.

x = 7 is 7 kg of water.

Not standard Salt should be added....It's about dividing 6,200 by 1,100 and looking at five points, and then subtracting five to get the difference is the amount added.