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olga nikolaevna [1]
3 years ago
8

Models need to be changed when _______.

Chemistry
1 answer:
dedylja [7]3 years ago
8 0
B. When scientific understanding changes. 
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Another chemistry question. Help me!
UkoKoshka [18]

Answer:

Molar mass Na2CO3 = 2*23 + 12 + 3*16 = 106 g/ mol

Mass of 1 mol Na2CO3 = 106 g

mass (Na2CO3) = 106g*250cm³/1000cm³ = 26.5 g

1) It is necessary because all Na2CO3 will be in the solution, and no Na2CO3 would be lost.

2) Because the solution that was formed after rinsing beaker contains Na2CO3.

3) Eyes should be on the level of calibration mark of the volumetric flask.

4) It is necessary to prevent evaporation of water, and changing , because of it, the concentration of the solution.

3 0
4 years ago
If a car traveling at 75 mph west, changes its direction to east, does its acceleration change?
Orlov [11]

Answer:

No because it changes velocity, instead of accelerating

Explanation:

and yes, I am in K12 ツ

5 0
3 years ago
Read 2 more answers
How many atoms are in 1.22 moles of magnesium?
WITCHER [35]

Answer:

7.34684 × 10^23 atoms

Explanation:

Well, one mole is basically

6.022 × 10^23 atoms. So 1.22 moles would be

6.022 × 10^23 ⋅ 1.22 atoms.

6.022 × 10^23 ⋅ 1.22 = 7.34684 × 10^23 atoms

7 0
3 years ago
Read 2 more answers
Assuming that the F−18 can be transported at 59.0 miles/hour, how close must the hospital be to the cyclotron if 68% of the F−18
tekilochka [14]

Answer:

60.12 miles

Explanation:

Using the calculation formula shown below:

t_{1/2} =\frac{t}{[tex]log_{2}\frac{N_{o} }{N_{t} } }[/tex]

where:

t_{1/2} is the half life, N_{o} is the original amount of F-18, and N_{t} is the remaining amount of F-18 at time t.

Generally, F-18 has an half life of 1.83 hours.

Therefore:

t = 1.83*[tex]log_{2}\frac{100}{68} = 1.02 hours[/tex]

Therefore using a speed of 59 miles/hour, the closeness of the hospital is:

distance = speed*time = 59*1.02 = 60.12 miles

6 0
3 years ago
Think and infer:
galben [10]
Idk So sorry for that
5 0
4 years ago
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