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3 years ago

If each water molecule contains 2 hydrogen atoms, how many total oxygen atoms in 20 water molecules?

1 answer:

7 0

The answer is 10 because if their is 20 molecules of hydrogen then their is one oxygen molecule for each which results in 20 divided by two which equals 10

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The half-life of radium-226 is 1590 years. if a sample contains 100 mg, how many mg will remain after 1000 years?

Katyanochek1 [597]

Answer:

$a=64.7mg$

Explanation:

Hello,

In this case, we need to remember that for the required time for a radioactive nuclide as radium-226 to decrease to one half its initial amount we are talking about its half-life. Furthermore, the amount of remaining radioactive material as a function of the half-lives is computed as follows:

$a=a_0(\frac{1}{2} )^{\frac{t}{t_{1/2}} }$

Therefore, for an initial amount of 100 mg with a half-life of 1590 years, after 1000 years, we have:

$a=100mg(\frac{1}{2} )^{\frac{1000years}{1590years} }\\\\a=64.7mg$

Best regards.

4 0

3 years ago

What amount of heat is required to raise the temperature of 350 grams of copper to cause a 25°C change? The specific heat of cop

jarptica [38.1K]

The heat required to raise the temperature to a specific temperature change of a sample is related to the specific heat capacity of the substance. In this case, the heat can be calculated through mCpΔT = 350 g * 0.39 J/g C *25 C. This is equal to 3412. 5 Joules. Closest answer is C.

4 0

3 years ago

Read 2 more answers

What does the atomic mass of an element on the periodic table represent?

Lynna [10]

The atomic mass on the periodic table represents the sum of number of protons and number of neutrons.

Atomic mass = Number of protons + number of neutrons

Hope this helps!

3 0

3 years ago

Vanillin (used to flavor vanilla ice cream and other foods) is the substance whose aroma the human nose detects in the smallest

balu736 [363]

Answer:

Cost to supply enough vanillin is $3.2\$$

Explanation:

Threshold limit of vanillin in air is $2.0\times 10^{-11}g$ per litre means there should be $2.0\times 10^{-11}g$ of vanillin in 1L of air to detect aroma of vanillin.

$1ft^{3}=28.32L$

So, $5.0\times 10^{7}ft^{3}=(5.0\times 10^{7}\times 28.32)L$

So amount of vanillin should be present to detect = $(2.0\times 10^{-11}\times 5.0\times 10^{7}\times 28.32)g$

As cost of 50 g vanillin is $112\$$ therefore cost of $(2.0\times 10^{-11}\times 5.0\times 10^{7}\times 28.32)g$ vanillin = $(2.0\times 10^{-11}\times 5.0\times 10^{7}\times 28.32\times 112)\$ = 3.2\$$

5 0

3 years ago

Which of the following is a monatomic anion? a) NH4+ b) Fr+ c) SO42– d) F-

Y_Kistochka [10]

I think that it's d) F- but I'm not sure.

8 0

3 years ago

Read 2 more answers