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Alex787 [66]
2 years ago
15

How did scientists find out about atoms before technology?

Chemistry
1 answer:
sasho [114]2 years ago
6 0

Answer:

There are three ways that scientists have proved that these sub-atomic particles exist. They are direct observation, indirect observation or inferred presence and predictions from theory or conjecture. Scientists in the 1800's were able to infer a lot about the sub-atomic world from chemistry.

Explanation:

Hope this helps

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Explain why an indicator is used in titration
stellarik [79]

Answer:

Titrations. Because a noticeable pH change occurs near the equivalence point of acid-base titrations, an indicator can be used to signal the end of a titration. When selecting an indicator for acid-base titrations, choose an indicator whose pH range falls within the pH change of the reaction.

Hope it helped!!

4 0
2 years ago
Find the mass of 0.235 moles of SiO2? (NOTE: use correct significant figures!)
marta [7]

Answer: 14.1g

Explanation:

Given that,

number of moles of SiO2 = 0.235 moles

Mass in grams = Z (let unknown value be Z)

Molar mass of SiO2 = ?

To get the molar mass of SiO2, use the atomic mass

Silicon = 28g;

Oxygen = 16g

i.e Molar mass of SiO2 = 28g + (16g x 2)

= 28g + 32g

= 60g/mol

Now, apply the formula

Number of moles = Mass / molar mass

0.235 moles = Z / 60g/mol

Z = 0.235 moles x 60g/mol

Z = 14.1 g

Thus, the mass of SiO2 is 14.1 grams.

8 0
2 years ago
HELP PLZ ITS A TEST.
tensa zangetsu [6.8K]

Answer:

The answer to your question is below

Explanation:

1 ) Which of the following is a chemical property.

A. Ability to become magnetic  this is wrong, it's a physical property

B. Ability to conduct electricity   this is wrong, it's a physical property

C. Ability to conduct heat   this is wrong, it's a physical property

D. Ability to react with acid This is the right answer

2 ) You heat two substances, A and B. Both substances change color. When cooled, substance B returns to its original color, but substance A does not. What most likely happened?.

A. Physical change occurred in both substances   This is wrong, a physial change only happens in substance B

B. A physical change occurred in substance A, and a chemical change occured in substance B.  This is wrong, a physical change occurred in substance B and a chemical change occurred in substance A.

C. A chemical change occurred in substance A, and a physical change occurred in substance B.  This is the right answer is exactly what happens

D. A chemical change occurred in both substances  This answer is wrong.

3 ) how many grams are in 2.5 pound sample? Express your answer in scientific notation with three significant figures. ( 1 pound= 453.592 grams).

Rule of three

    1 pound ------------------- 453.592 g

  2.5 pounds ---------------   x

  x = 2.5(453.592)/1

  x = 1133.98 g = 1.13 x 10³ g    letter D

7 0
2 years ago
Read 2 more answers
I will give Brainliest!!! What kind of atoms makeup C12H22O11?
Goshia [24]

Answer:

carbon, hydrogen, and oxygen atoms

Explanation:

brainliest pls

7 0
2 years ago
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I NEED HELP ANSWERING THESE QUESTIONS FOR 50 POINTS!!!!!
Semmy [17]
The answers are true, true, false, true, and false.
7 0
3 years ago
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