Answer:
[(x-37.5)/x]*100%
62.5% (assuming the original sample weighs 100.0g)
Explanation:
Let's say that the original sample is x
Mass of I-125 which has decayed: x-37.5
Percentage of decayed mass: [(x-37.5)/x]*100%
Please recheck, for this may not be the correct answer
Hello!
If a sample contains 21.2 g N, how many moles of N does it contain?
0.66 mol
1.51 mol
14.01 mol
297.01 mol
We have the following data:
m (mass) = 21.2 g
MM (Molar mass of Nitrogen) = 14 g / mol
n (number of moles) = ?
Formula:

Solving:



Answer:
1.51 mol
_______________________________
I Hope this helps, greetings ... Dexteright02! =)
To solve this question, you must use the formula: q=mc(change in temperature), where q is heat, m is mass, C is specific heat and temperature change is temperature change. The specific heat for ice is 2.1kJ/Kg x K (given). The change in temperature is 15 degrees Celsius (which you should change to kelvins so you can cancel out units), or 273 + 15 = 288K. The mass is 150 grams, which is 0.15 kg. Now, we can solve for q, heat. We will do this by substituting variables into the formula. After simplifying and cancelling out units, the answer we get is: 90.72kJ.
Answer:
BaSO₄
Explanation:
Let's assume we have 100 g of the compound. If that's the case we would have:
Now we <u>convert the masses of each element into moles</u>, using their <em>respective molar masses</em>:
- 58.8 g Ba ÷ 137.327 g/mol = 0.428 mol Ba
- 13.74 g S ÷ 32 g/mol = 0.429 mol S
- 27.43 g O ÷ 16 g/mol = 1.71 mol O
We <u>divide those moles by the lowest number among them</u>:
We can express those results as Ba₁S₁O₄, meaning the empirical formula is thus BaSO₄.
The statement about the formation of the solar system that
are true and in a correct order are Gravitational force held the newly formed
planets around the sun; small planetary objects formed; hydrogen and helium
became concentrated in the outer solar system to form the outer planets. The answer
is letter D.