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Nesterboy [21]
3 years ago
14

How long does it take for 87.5 % of each isotope to decay?

Chemistry
1 answer:
Zolol [24]3 years ago
7 0

Answer:

Kr-73 = 23.625 sec

Kr-74 = 10.0625 minutes (603.75 seconds)

Kr-76 = 12.95 hours (777 minutes)

Kr-81 = 1.8375 * 10^6 years

Explanation:

What you do is multiply each of those amounts by 7/8.

27 * 7/8 = 189/8 = 23.625

23/2 * 7/8 = 161/16 = 10.0625

74/5 * 7/8 = 518/40 = 259/20 = 12.95

210000 * 7/8 = 1470000/8 = 183750 = 1.8375 * 10^6

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for the following reaction how many grams of h20 will be produced if you react 3.7 grams of B2H6? B2h6 +3O2-2hbo2+ 2 H20
Nana76 [90]

Answer:

4.8 g H₂O

Explanation:

To find the mass of water, you need to (1) convert grams B₂H₆ to moles B₂H₆ (via molar mass from periodic table), then (2) convert moles B₂H₆ to moles H₂O (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles H₂O to grams H₂O (via molar mass from periodic table).

It is important to arrange the ratios/conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 2 sig figs because the given value (3.7 grams) has 2 sig figs.

Molar Mass (B₂H₆): 2(10.811 g/mol) + 6(1.008 g/mol)

Molar Mass (B₂H₆): 27.67 g/mol

1 B₂H₆ + 3 O₂ ---> 2 HBO₂ + 2 H₂O
^                                             ^

Molar Mass (H₂O): 15.998 g/mol + 2(1.008 g/mol)

Molar Mass (H₂O): 18.014 g/mol

3.7 g B₂H₆          1 mole            2 moles H₂O           18.014 g
----------------  x  ---------------  x  -----------------------  x  -----------------  =  4.8 g H₂O
                          27.67 g           1 mole B₂H₆              1 mole

6 0
2 years ago
C3H8 + 5O2 → 3CO2+ 4H2O, if 5.75L of oxygen are consumed in the above reaction, how many L of carbon dioxide are produced?
anzhelika [568]

Answer: 3.45 L carbon dioxide are produced

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 6.023\times 10^{23} of particles.

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given volume}}{\text {Molar volume}}=\frac{5.75L}{22.4L}=0.257moles

C_3H_8+5O_2(g)\rightarrow 3CO_2+4H_2O  

According to stoichiometry :

5 moles of O_2 produce =  3 moles of CO_2

Thus 0.257 moles of O_2 will produce=\frac{3}{5}\times 0.257=0.154moles  of CO_2  

Volume of CO_2=moles\times {\text {Molar volume}}=0.154moles\times 22.4L/mol=3.45

Thus 3.45 L carbon dioxide are produced

6 0
3 years ago
Does the biosphere have clear boundaries
Ne4ueva [31]

No, the biosphere does not exhibit a clear boundary as life always comes to an end.  

The biosphere comprises all the living things of the world, like all the plants and animals. It is considered as the global ecosystem, that is, the gathering of all the planet's ecosystems. It comprises the land and the atmosphere. It is usually considered as the zone of life, where all the species of the planet thrives.  


7 0
3 years ago
there is an ice cream shop 6 blocks north of your hotel. how many minutes will it take to walk there and back
Allushta [10]

Answer:

This question is incomplete

Explanation:

This question is incomplete.

However, when all the required data are available, you can use the formula/steps below

Average speed/velocity (m/s) = distance (in metres) ÷ time (in seconds)

Time (in secs) = distance ÷ average speed/velocity

Kindly note that "blocks" is not a standard unit for distance measurement in science, hence the distance (since its a walking distance) must be in metres (or converted to metres if not in metres).

The distance in the formula is the distance from the hotel to the ice cream shop while the average speed is the distance covered per time as s/he walks to the ice cream shop and back. Hence, the answer gotten from the formula above will have to be multiplied by 2 (in order to get the time taken to walk to the ice cream shop and back) because the formula will only provide answer to one trip (time taken to walk to the shop).

After the multiplication mentioned above, the time in seconds should be converted to minutes by dividing the answer in seconds by 60

8 0
3 years ago
para una practica de laboratorio se requiere una disolucion de acido nitrico HNO3 al 3,5M,pero se dispone de un frasco de 1 litr
aliya0001 [1]

Answer:

hindi ko alam yan

PANO BA YAN

Explanation:

EWAN

5 0
3 years ago
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