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inn [45]
3 years ago
13

a radioactive substance has a half-life of 10 years.if you start with 30 grams of the substance, how much will remain after 30 y

ears.
Chemistry
1 answer:
Bess [88]3 years ago
7 0
Your answer is 9,000. If you times 30 by 10 you’ll get 300, that’s how many grams you’ll have in 10 years. If you want to know how many grams you’ll have in 30 years you will get 9,000
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A thermometer having first-order dynamics with a time constant of 1 min is placed in a temperature bath at 100oF. After the ther
sveticcg [70]

Answer:

(a) See below

(b) 103.935 °F; 102.235 °F

Explanation:

The equation relating the temperature to time is

T = T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )

1. Calculate the thermometer readings after  0.5 min and 1 min

(a) After 0.5 min

\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )\\ & = & 100 + 10\left (1 - e^{-0.5/1} \right )\\ & = & 100 + 10\left (1 - e^{-0.5} \right )\\ & = & 100 + 10 (1 - 0.6065)\\ & = & 100 + 10(0.3935)\\ & = & 100 + 3.935\\ & = & 103.935\,^{\circ}F\\\end{array}

(b) After 1 min

\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-t/\tau} \right )\\ & = & 100 + 10\left (1 - e^{-1/1} \right )\\ & = & 100 + 10\left (1 - e^{-1} \right )\\ & = & 100 + 10 (1 - 0.3679)\\ & = & 100 + 10(0.6321)\\ & = & 100 + 6.321\\ & = & 106.321\,^{\circ}F\\\end{array}

2. Calculate the thermometer reading after 2.0 min

T₀ =106.321 °F

ΔT = 100 - 106.321 °F = -6.321 °F

  t = t - 1, because the cooling starts 1 min late

\begin{array}{rcl}T & = & T_{0} + \Delta T\left (1 - e^{-(t - 1)/\tau} \right )\\ & = & 106.321 - 6.321\left (1 - e^{-(2 - 1)/1} \right )\\ & = & 106.321 - 6.321\left (1 - e^{-1} \right )\\ & = & 106.321 - 6.321 (1 - 0.3679)\\ & = & 106.321 - 6.321 (0.6321)\\ & = & 106.321 - 3.996\\ & = & 102.325\,^{\circ}F\\\end{array}

3. Plot the temperature readings as a function of time.

The graphs are shown below.

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3 years ago
balance the following equation and then find the mole ratio of Mg and Mn in the equation Mg + Mn2O3 --> MgO + Mn
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Answer:

3Mg + Mn2O3 → 3MgO + 2Mn

Explanation:

I think this is how to balance I really don't understand the rest, I have not done this in years sorry!

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Use the Earth's Energy Budget diagram to answer the question. Based on the diagram, less solar energy that reaches Earth is ____
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<span>absorbed, radiated
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The product of alpha decay of the Nobelium isotope 259No is
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Answer:

Nobelium is made by the bombardment of curium (Cm) with carbon nuclei. Its most stable isotope, 259No, has a half-life of 58 minutes and decays to Fermium (255Fm) through alpha decay or to Mendelevium (259Md) through electron capture.

Explanation:

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