The answer is <span>(3) 3 × 12.4 hours
</span>
To calculate this, we will use two equations:


where:
<span>n - number of half-lives
</span>x - remained amount of the sample, in decimals
<span>

- half-life length
</span>t - total time elapsed.
First, we have to calculate x and n. x is <span>remained amount of the sample, so if at the beginning were 16 grams of potassium-42, and now it remained 2 grams, then x is:
2 grams : x % = 16 grams : 100 %
x = 2 grams </span>× 100 percent ÷ 16 grams
x = 12.5% = 0.125
Thus:
<span>

</span>




It is known that the half-life of potassium-42 is 12.36 ≈ 12.4 hours.
Thus:
<span>

</span><span>

</span>

Therefore, it must elapse 3 × 12.4 hours <span>before 16 grams of potassium-42 decays, leaving 2 grams of the original isotope</span>
1 mol = 6.022 x 10²³ atoms
In order to find how many atoms, dimly multiply the amount of moles you have by 6.022 x 10²³ or Avogadro's number.
So you have 1.75 mol CHC1₃ x (6.022x10²³) = 1.05385 x 10²⁴ atoms of CHCl₃
But now you have to round because of the rules of significant figures so you get 1.05 x 10²⁴ atoms of CHCl₃
Answer:
Energy is transferred from one object to another when a reaction takes place.
Explanation:
Energy comes in many forms and can be transferred from one object to another as heat, light, or motion, to name a few.
The answer could be It is a well known fact that energy can neither be created and nor be destroyed but can be transformed from one form to another.
Now talking about your example in a typical light bulb electrical energy is converted into light energy and heat energy. Now when the electric current flows through the conductor/filament in the light bulb,this would cause vibrations and the free ions are more likely to go to an higher energy level,and when the ions come back to their original state,the difference in the two energy levels is usually emitted as a photon,thus light energy is obtained and the heat energy is the energy dissipated as a result of flow of electricity through the conductor.
Anything that gets transformed into light energy or in better words ElectroMagnetic Energy would be a result of this.