## MTALHAHASSAN2 one year ago Hydrogen-3 has a half-life of 12.35 years. What mass of hydrogen-3 will remain form a 100.0 MG initial sample after 5.0 years? A) 7 MG B) 24 MG C) 76 MG D) 18 MG

1. MTALHAHASSAN2

@wio

2. MTALHAHASSAN2

@souvik

3. MTALHAHASSAN2

4. MTALHAHASSAN2

Plz

5. Astrophysics

We will have to use the following $\huge \frac{ m_f }{ m_i } = \left( \frac{ 1 }{ 2 } \right)^{\left( \frac{ t }{ T^{1/2} } \right)}$ where $T^{1/2} = \text{half life}$ $t =\text{ time}$ $m_f = \text{final mass}$ $m_i = \text{initial mass}$

6. Astrophysics

So let me ask you, what are we solving for here?

7. MTALHAHASSAN2

Final mass

8. Astrophysics

Right!

9. Astrophysics

So our formula then becomes $\huge m_f = m_i \left( \frac{ 1 }{ 2 } \right)^{\frac{ t }{ T^{\frac{ 1 }{ 2 }} }}$ right?

10. Astrophysics

Now at this stage, you just need to plug in the values

11. Astrophysics

and evaluate

12. MTALHAHASSAN2

So what u get

13. Astrophysics

I think you can at least do that much.

14. MTALHAHASSAN2

Wait what we put for T 1/2

15. Astrophysics

Don't let the 1/2 confuse you, I put it there to represent half life, that is 12.35 years

16. MTALHAHASSAN2

Oh ok

17. MTALHAHASSAN2

I am getting a very big number

18. Astrophysics

$\huge m_f = (100MG)(1/2)^{\frac{ 5.0 }{ 12.35 }}$

19. MTALHAHASSAN2

Know I get 76

20. Astrophysics

Yup :)

21. MTALHAHASSAN2

Thnx alot

22. Astrophysics

Np