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bulgar [2K]
3 years ago
5

Cobalt-60, with a half-life of 5.0 days, is used in cancer radiation treatments. A hospital purchases a 30.0g supply of it and s

tores it on a shelf in a closet. The next time a hospital worker grabs the bottle, though, they find that it only contains 3.75 g remaining! Assuming the bottle had never been opened, how long was the bottle sitting on the shelf before the worked grabbed it?
Chemistry
1 answer:
Rudik [331]3 years ago
8 0

Answer:

Bottle is sitting on the shelf for 15 days.

Explanation:

Given data:

Co-60 half life = 5 days

Total amount = 30.0 g

Amount left = 3.75 g

Time taken = ?

Solution:

AT time zero = 30 g

AT first half life= 30g /2 = 15 g

At 2nd half life = 15 g/ 2 = 7.5 g

At 3rd half life = 7.5 g/2 = 3.75 g

Now we will calculate the sitting time of bottle.

Half life = Time taken / number of half lives

3× 5 days = time taken

Time taken = 15 days

Bottle is sitting on the shelf for 15 days.

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Decreasing the temperature of a reaction decreases the reaction rate because
Elza [17]
The answer u are looking for is b
4 0
3 years ago
Read 2 more answers
Compare 1 mole of H2, 1 mole of O2, and 1 mole of F2. (a) Which has the largest number of molecules? Explain why. (b) Which has
AURORKA [14]

<u>a) Answer: </u>

<em>Number of molecules in 1 mole</em>

<u>Explanation:</u>

a) Whether we take any of the substance among all three of the given substances they will have the same number of molecules in 1 mole of the substance is considered and the value for this will be 6.023 x 10^23

<u>b)  Answer: </u>

<em>In the given question </em><em>mass of the substance</em><em> which is </em><em>greatest</em><em> is asked for </em><em>one mole</em><em> and we also know that </em><em>mass of one mole is given by molar mass.  </em>

<u>Explanation:</u>

b) It is known that 31.98g/mol is the molar mass for oxygen which is greater than that of hydrogen while fluorine has a molar mass of 38.0 g/mol which on comparison shows that, it is the highest amongst all three.

3 0
3 years ago
Solutions are said to be what kind of mixture? A) Pure substance B) Heterogeneous C) Homogenous D) Element
laiz [17]
Solutions are said to be C. homogeneous mixtures, composed of two or more substances. It is usually liquid, however it may be solid or gas.
7 0
3 years ago
A serving of Cheez-Its releases 130 kcal (1 kcal = 4.18 kJ) when digested by your body. If this same amount of energy were trans
Brut [27]

The final temperature : 78.925°C

<h3>Further explanation  </h3>

Heat can be calculated using the formula:  

Q = mc∆T  

Q = heat, J  

m = mass, g  

c = specific heat, joules / g ° C  

∆T = temperature difference, ° C / K  

Energy releases = 130 kcal = 130 x 4.18 kJ=543.4 kJ

The final temperature :

\tt \Delta T=\dfrac{Q}{m.c}\\\\\Delta T=\dfrac{543.4}{2.5\times 4.186~kJ/kg^oC}\\\\\Delta T=51.925^oC

Final temperature :

ΔT=final-initial

51.925°c=final-27°c

final = 51.925+27=78.925°C

7 0
2 years ago
you wish to make a 0.161 m hydroiodic acid solution from a stock solution of 3.00 m hydroiodic acid. how much concentrated acid
mestny [16]

5.367 ml of the concentrated acid must be added to obtain a total volume of 100 ml of the dilute solution.

Dilution is defined as the process in which the concentration of a sample is decreased by adding more solvent. The dilution formula is given below.

C₁V₁ = C₂V₂

where C₁ = initial concentration of sample = 3.00 m

V₁ = initial volume of sample

C₂ = final concentration after dilution = 0.161 m

V₂ = total final volume after dilution = 100 ml

Plug in the values to the formula and solve for the volume of the concentrated acid that must be added.

C₁V₁ = C₂V₂

3.00 m (V₁) = 0.161 m (100 ml)

V₁ = 5.367 ml

Learn more about dilution here: brainly.com/question/1615979

#SPJ4

3 0
1 year ago
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