How many half-lives must elapse until 84 % of a radioactive sample of atoms has decayed? -g?

1 answer:

4 0

Half-life is the time required for decay of 50% of radio-active nuclei.

Thus, when radio-active material crosses 1st half-life, 100/2 = 50% radio-active material is left and remaining 50% is elapsed.

When, when radio-active material crosses 2nd half-life, 50/2 = 25% radio-active material is left and remaining 75% is elapsed.

When radio-active material crosses 3rd half-life, 25/2 = 12.5% radio-active material is left and remaining 87.5% is elapsed.

Thus, 2 <span>half-lives must elapse until 84 % of a radioactive sample of atoms has decayed.</span>

You might be interested in

What happens when the pressure of a gas is decreased?

Serggg [28]

Answer:

The combined gas law states that the pressure of a gas is inversely related to the volume and directly related to the temperature. If temperature is held constant, the equation is reduced to Boyle's law. Therefore, if you decrease the pressure of a fixed amount of gas, its volume will increase.

Explanation:

3 0

3 years ago

A solution is prepared by dissolving 8.75 grams of sodium chloride in enough volume of water to produce 112.0 grams of the NaCl

ICE Princess25 [194]

Answer : The percent by mass of the solution is 7.81 %

Explanation : Given,

Mass of NaCl = 8.75 g

Mass of solution = 112.0 g

Now we have to determine the percent by mass of the solution.

$\text{Mass percent}=\frac{\text{Mass of NaCl}}{\text{Mass of solution}}\times 100$

Putting values in above equation, we get:

$\text{Mass percent}=\frac{8.75g}{112.0g}\times 100=7.81\%$

Therefore, the percent by mass of the solution is 7.81 %

6 0

3 years ago

Chemistry help please! I just need to make sure the answers correct.... Thank you!

Veronika [31]

1. At constant tempaerature and pressure, 3 tablets produce 600cm^3 of gas
Thus calculating for 1 tablet that produces 600 / 3 = 200 cm^3
So now two tablets produce 200 x 2 = 400 cm^3
2. We have the equation PV = nRT, n being the number of moles
Pressure P = 1,000 kPa
Volume V = 3 L
R = 8.31 L kPa/mol-K
Temperature T = 298 K
n = PV / RT = (1000 x 3) / (8.31 x 298) = 3000 / 2476.38 = 1.21 moles
Number of moles = 1.21 moles.

8 0

3 years ago

Explain how the fire spreading from tree to tree provides a model for conduction.

Inessa05 [86]

the fire spreading is what represents the form of heat transferring from one atom to another within an object and direct contact

6 0

3 years ago

What force is causing The object to eventually stop moving

hichkok12 [17]

Answer:

Hey buddy, here is your answer. Hope it helps you.

Explanation:

The force stopping the object's motion might be an obvious one - the ground! Friction is a force that slows or stops motion. Friction is the resistance to motion created by two objects rubbing against each other (the sled and the snow, for instance). Even air causes friction.

3 0

3 years ago