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Marat540 [252]
3 years ago
6

Which of these is an example of a physical change ?

Chemistry
1 answer:
Gre4nikov [31]3 years ago
8 0
It's 1. Melting a substance. The rest are chemical changes
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Calculate the ph of sweater which has a hydrogen ion concentration of 1 times 10 to the power of 8
telo118 [61]

Answer:

The pH of the sweater containing Hydrogen ion concentration

[H^{+}]=1\times 10^{-8} is

<u>8</u>

<u></u>

Explanation:

pH = It is the negative logarithm of activity (concentration) of hydrogen ions.

pH = -log([H+])

Now, In the question the concentration of [H+] ions is :

[H^{+}]=1\times 10^{-8}

pH = -log(1\times 10^{-8})

use the relation:

log(10^{-a})=a

pH= -(-8)

pH = 8

Note : <em><u> 1 times 10 to the power of 8 must be" 1 times 10 to the power of -8"</u></em>

If the concentration is

[H^{+}]=1\times 10^{8}

Then pH = -8 , which is not possible . So in that  case the pH calculation is by other method

5 0
3 years ago
Pls help me with this atomic number worksheet I will make you the brainiest worth 25 points
ELEN [110]

Answer:

HELLO THERE!

I HOPE MY ANSWER WILL HELP YOU :)

Explanation:

PLEASE NOTE; I HAVE WRITTEN THE ATOMIC NUMBER IN BRACKETS, NEXT TO THE SYMBOL OF THE ELEMENT

7 0
2 years ago
If salt is dissolved in water, water serves as the:
NemiM [27]
B. solvent 

solute is the substance being dissolved
5 0
3 years ago
Arrange the following H atom electron transitions in order of decreasing wavelength of the photon absorbed or emitted:
Katyanochek1 [597]

The decreasing order of wavelengths of the photons emitted or absorbed by the H atom is : b → c → a → d

Rydberg's formula :

                                   \frac{1}{\lambda} = R_h (\frac{1}{n_1^2}-\frac{1}{n_2^2} ),

where  λ is the wavelength of the photon emitted or absorbed from an H atom electron transition from n_1 to n_2 and R_h = 109677 is the Rydberg Constant. Here n_1 and  n_2 represents the transitions.

(a) n_1 =2 to n_2 = infinity

            \frac{1}{\lambda} = 109677\times (\frac{1}{2^2}-\frac{1}{\infty^2}  ) = 109677/4     [since 1/infinity = 0] Therefore, \lambda = 4 / 109677 = 0.00003647 m

(b) n_1=4 to  n_2 = 20

           \frac{1}{\lambda} = 109677\times (\frac{1}{4^2}-\frac{1}{20^2}  ) = 6580.62

Therefore,  \lambda = 1 / 6580.62 = 0.000152 m

(c) n_1=3 to  n_2 = 10

          \frac{1}{\lambda} = 109677\times (\frac{1}{3^2}-\frac{1}{10^2}  ) = 11089.56

Therefore,  \lambda = 1 / 11089.56 = 0.00009 m

(d)  n_1=2 to  n_2 = 1

          \frac{1}{\lambda} = 109677\times (\frac{1}{2^2}-\frac{1}{1^2}  ) = - 82257.75

Therefore,  \lambda = 1 /82257.75  = - 0.0000121 m  

[Even though there is a negative sign, the magnitude is only considered because the sign denotes that energy is emitted.]

So the decreasing order of wavelength of the photon absorbed or emitted is b → c → a → d.

Learn more about the Rydberg's formula athttps://brainly.com/question/14649374

#SPJ4

8 0
1 year ago
Which is a reason that a chemical engineer would use a rate law for a reaction in a chemical plant?
Harrizon [31]
<span>A.to calculate the amount of product that would form

</span>
5 0
3 years ago
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