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3 years ago

According to your study unit, what's the payoff that keeps volunteers using their own time to help their communities?

1 answer:

8 0

C. It's so rewarding, people feel emotionally high and fulfilled when they're done.

In volunteering, your primary motivation is to extend your help or assistance and make other people happy. Seeing people happy because of what you are doing, it the ultimate reward of volunteering. Happiness gained from this experience is priceless. It is worth more than any freebies or any material gains you will receive.

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Uranium is a metallic element that is used in nuclear reactors and nuclear weapons. the vast majority of uranium found on earth

katrin [286]

There will be 143 neutrons in uranium-235

7 0

4 years ago

What is the volume of 0.80 grams of O2 gas at STP? (5 points) Group of answer choices 0.59 liters 0.56 liters 0.50 liters 0.47 l

Anarel [89]

Answer:

0.56 liters

Explanation:

First we <u>convert 0.80 grams of O₂ into moles</u>, using its molar mass:

0.80 g ÷ 32 g/mol = 0.025 mol

At STP, 1 mol of any given mass occupies 22.4 L. With that information in mind we <u>calculate the volume that 0.025 moles of O₂ gas would occupy</u>:

0.025 mol * 22.4 L/mol = 0.56 L

Thus the answer is 0.56 liters.

3 0

3 years ago

A certain radioactive isotope decays at a rate of 0.2% annually. Determine the half-life of this isotope, to the nearest year

pychu [463]

Answer:

The half-life of the radioactive isotope is 346 years.

Explanation:

The decay rate of the isotope is modelled after the following first-order linear ordinary differential equation:

$\frac{dm}{dt} = -\frac{m}{\tau}$

Where:

$m$ - Current isotope mass, measured in kilograms.

$t$ - Time, measured in years.

$\tau$ - Time constant, measured in years.

The solution of this differential equation is:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$

Where $m_{o}$ is the initial mass of the isotope. It is known that radioactive isotope decays at a yearly rate of 0.2 % annually, then, the following relationship is obtained:

$\%e = \frac{m(t)-m(t+1)}{m(t)}\times 100\,\% = 0.2\,\%$

$1 - \frac{m(t+1)}{m(t)} = 0.002$

$1 - \frac{m_{o}\cdot e^{-\frac{t+1}{\tau} }}{m_{o}\cdot e^{-\frac{t}{\tau} }}=0.002$

$1 - e^{-\frac{1}{\tau} } = 0.002$

$e^{-\frac{1}{\tau} } = 0.998$

$-\frac{1}{\tau} = \ln 0.998$

The time constant associated to the decay is:

$\tau = -\frac{1}{\ln 0.998}$

$\tau \approx 499.500\,years$

Finally, the half-life of the isotope as a function of time constant is given by the expression described below:

$t_{1/2} = \tau \cdot \ln 2$

If $\tau \approx 499.500\,years$ , the half-life of the isotope is:

$t_{1/2} = (499.500\,years)\cdot \ln 2$

$t_{1/2}\approx 346.227\,years$

The half-life of the radioactive isotope is 346 years.

6 0

3 years ago

What is a chemical formula, and what does it tell you?

katrin2010 [14]

Explanation:

chemical formula tells you the specific elements included in the compound and the number of atoms of each. The letters in a chemical formula are the symbols for the specific elements. So for example, H means hydrogen.

7 0

3 years ago

Read 2 more answers

PLEASE HELP ITS VERY EASY FOR OTHER PLEASE ITS A TEST DUE IN AN HOUR PLEASEEEEEEEEEE

GalinKa [24]

Answer:

Large objects close together

8 0

3 years ago