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Tju [1.3M]
3 years ago
8

A scientist performs an experiment in which a radium–226 (Ra–226) atom decays into radon–222 (Rn–222). The scientist concludes t

hat some energy must have been added to the system to cause this reaction to begin. Which would disprove his conclusion?
A) Radium–226 is an unstable isotope of radium.
B) Radon–222 is an unstable isotope of radon.
C) The decay released an alpha particle.
D) The decay released a beta particle and a gamma ray.
Chemistry
2 answers:
Agata [3.3K]3 years ago
8 0

Answer:

A) Radium-226 is an unstable isotope of radon

Explanation:

This was correct on my test

tangare [24]3 years ago
5 0

Answer:

B)

Explanation:

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An object is uniformly accelerated from rest to a speed of 35 meters per second in 7 seconds. The acceleration of the object is
gavmur [86]
Its 5m/s because you have to find out how many meters for one second so you divide
35/7=5 so that's your answer
3 0
3 years ago
Read 2 more answers
The complete combustion of propane (C3H8) in the presence of oxygen yields CO2 and H2O: C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (g) a
mixas84 [53]

Answer:

26.9 L is the volume of CO₂, we obtained

Explanation:

The reaction is: C₃H₈(g) + 5O₂(g)  →  3CO₂ (g) + 4H₂O (g)

Let's determine the reactants moles:

27.5 g . 1mol / 44 g = 0.625 moles

We need density of O₂ to determine mass and then, the moles.

O₂ density = O₂ mass / O₂ volume

O₂ density . O₂ volume = O₂ mass

1.429 g/L . 45L = O₂ mass → 64.3 g

Moles of O₂ → 64.3 g . 1mol/32g = 2.009 moles

Let's find out the limiting reactant:

1 mol of propane needs 5 moles of oxygen to react

Then, 0.625 moles will react with (0.625 . 5)/1 = 3.125 moles of O₂

Oxygen is the limiting reactant, we need 3.125 moles but we only have 2.009 moles

Ratio is 5:3. 5 moles of O₂ produce 3 moles of CO₂

Therefore, 2.009 moles of O₂ must produce (2.009 .3) /5 = 1.21 moles of CO₂. Let's find out the volume, by Ideal Gases Law (STP are 1 atm and 273K, the standard conditions)

1 atm . V = 1.21 moles . 0.082 . 273K

V = (1.21 moles . 0.082 . 273K) / 1atm = 26.9 L

3 0
3 years ago
Dilution question In many of the experiments, you will be asked to prepare a standard solution by diluting a stock solution. You
riadik2000 [5.3K]

Answer:

We could do two 1:50 dilutions and one 1:4 dilutions.

Explanation:

Hi there!

A solution that is 1000 ug/ ml  (or 1000 mg / l) is 1000 ppm.

Knowing that 1 ppm = 1000 ppb, 100 ppb is 0.1 ppm.

Then, we have to dilute the stock solution (1000 ppm / 0.1 ppm) 10000 times.

We could do two 1:50 dilutions and one 1:4 dilutions (50 · 50 · 4 = 10000). Since the first dilution is 1:50, you will use the smallest quantity of the stock solution (if we use the 10.00 ml flask):

First step (1:50 dilution):

Take 0.2 ml of the stock solution using the third dispenser (20 - 200 ul), and pour it in the 10.00 ml flask. Fill with water to the mark (concentration : 1000 ppm / 50 = 20 ppm).

Step 2 (1:50 dilution):

Take 0.2 ml of the solution made in step 1 and pour it in another 10.00 ml flask. Fill with water to the mark. Concentration 20 ppm/ 50 = 0.4 ppm)

Step 3 (1:4 dilution):

Take 2.5 ml of the solution made in step 3 (using the first dispenser 1 - 5 ml) and pour it in a 10.00 ml flask. Fill with water to the mark. Concentration 0.4 ppm / 4 = 0.1 ppm = 100 ppb.

6 0
3 years ago
Any help with atomic radius, ionization & electronegativity? See picture please! I dont really understand any of the three.​
enyata [817]
18)
a. Ra
d. Ag
19)
a. C
b. Br
c. Mg
20)
a. S
b. Br
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Sorry wasn’t sure about some of them in #18
Hope the notes are helpful.

8 0
2 years ago
What do all viruses have in common? Choose more than one answer.
vitfil [10]

Answer:

1, 3, 4, and 5

Explanation:

the number would be the dot order!

7 0
2 years ago
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