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ddd [48]
3 years ago
8

The United States was the first modern

Chemistry
1 answer:
kicyunya [14]3 years ago
4 0

Answer:

first modern?

Explanation:

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If you were asked to convert 25 cg to the unit hg, which of the following would be the first fraction used in the conversion? on
zhannawk [14.2K]
We are asked to convert 25 cg to units of hg.

1 cg = 1 centigram = 10⁻² g
1 hg = 1 hectogram = 10² g

The options given are:

a) 1 hg/ 10² g
b) 10² cg/ 1 hg
c) 10² hg/ 1 cg
d) 10⁻² g/ 1 cg

To convert 25 cg to 1 hg, we could convert the 25 cg to grams first, then grams to hg.

25 cg · 10⁻² g/ 1cg = 0.25 g

Here we have converted our number from cg to grams. We can use another conversion of grams to hg to complete the conversion.

0.25 g · 1 hg/ 10² g = 0.0025 hg

Therefore, the first conversion we used was d) 10⁻² g/ 1 cg.
4 0
3 years ago
Why must the ph ammonia buffer solution be stored and dispensed in the fume exhaust hood?
Vadim26 [7]

On the other hand ammonia is a very dangerous chemical which has a pungent smell and effect the eyes of the user. Thus it kept always in the fume exhaust hood for storing and dispensing function.  

The  pH of ammonia buffer contains ammonium hydroxide (NH₄OH) and a salt of ammonia with a  strong acid like (HCl) which produces, ammonium chloride (NH₄Cl) mixture. The evaporation rate of ammonia is so high at room temperature thus on opening of the buffer solution the ammonia get evaporated very fast and the concentration of ammonia decreases which affect the pH of the buffer solution.

Thus the reason to put ammonia buffer in fume hood is explained.


7 0
3 years ago
If one mole of a substance has a mass of 56.0 g, what is the mass of 11 nanomoles of the substance? Express your answer in nanog
9966 [12]

Answer:

616,0 ng is the right answer.

Explanation:

You should know that 1 mole = 1 .10^9 nanomoles

Get the rule of three.

1 .10^9 nanomoles ...................... 56.0 gr

11 nanomoles .....................

(11 x 56) / 1 .10^9 nanomoles = 6.16 x 10^-7 gr

Let's convert

6.16 x 10^-7 gr x 1 .10^9 = 616 ngr

8 0
3 years ago
Which of the following isotopes is radioactive A)C-12 B)Pb-206 C) Tc-99 D)Ne-20
Gre4nikov [31]
C) Tc-99 is a radioactive isotope also known as radioisoptope. 
4 0
3 years ago
Silicon has a relatively large latent heat of vaporization of 12800 J/g. This indicates that silicon has:
Lesechka [4]

strong attraction between liquid particles

7 0
4 years ago
Read 2 more answers
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