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aev [14]
3 years ago
15

How many carbon atoms are present in 3.900 x 10-4 mol of carbon? Give your answer in scientific notation. x 10 (select) A

Chemistry
1 answer:
AnnyKZ [126]3 years ago
4 0

<u>Answer:</u> The number of atoms of carbon present in given number of moles are 2.350\times 10^{20}

<u>Explanation:</u>

We are given:

Number of moles of carbon = 3.900\times 10^{-4}mol

According to mole concept:

1 mole of an element contains 6.022\times 10^{23} number of atoms.

So, 3.900\times 10^{-4}mol of carbon will contain = 3.900\times 10^{-4}\times 6.022\times 10^{23}=2.350\times 10^{20} number of atoms.

Hence, the number of atoms of carbon present in given number of moles are 2.350\times 10^{20}

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How much work is needed to assemble an atomic nucleus containing three protons (such as Be) if we model it as an equilateral tri
klio [65]

Answer:

2.16 MeV

Explanation:

To determine the amount of work done that is needed to assemble the atomic mass; we need to apply the equation;

U = \frac{3}{4 \pi E_o} (\frac{e^2}{r})

where:

\frac{1}{4 \pi E_o} = proportionality constant = (9*10^9N.m^2/C^2)

e = magnitude of the charge of each electron = (1.6*10^{-19} C)^2

r = length of each side of the vertex = (2.00*10^{-15}m)

So; replacing our values into above equation; we have:

U = 3\frac{(9*10^9N.m^2/C^2)(1.6*10^{-19} C)^2}{(2.00*10^{-15}m)}

U = 3.456 × 10 ⁻¹³ J

If we have to convert our unit from J to Mev; then we are going to have:

U = 3.456 × 10 ⁻¹³ J (\frac{1 MeV}{1.602*10^{-13}J})

U = 2.16 MeV

Therefore, the amount of work done needed to assemble an atomic nucleus =  2.16 MeV

8 0
3 years ago
Carbon-14 is a radioactive isotope that decays according to first-order kinetics in a process that has a half-life of 5730 years
Sliva [168]

Answer : The time passed in years is 2.83\times 10^3\text{ years}

Explanation :

Half-life = 5730 years

First we have to calculate the rate constant, we use the formula :

k=\frac{0.693}{t_{1/2}}

k=\frac{0.693}{5730\text{ years}}

k=1.21\times 10^{-4}\text{ years}^{-1}

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant  = 1.21\times 10^{-4}\text{ years}^{-1}

t = time passed by the sample  = ?

a = let initial amount of the reactant  = X g

a - x = amount left after decay process = 71\% \times (x)=\frac{71}{100}\times (X)=0.71Xg

Now put all the given values in above equation, we get

t=\frac{2.303}{1.21\times 10^{-4}}\log\frac{X}{0.71X}

t=2831.00\text{ years}=2.83\times 10^3\text{ years}

Therefore, the time passed in years is 2.83\times 10^3\text{ years}

8 0
3 years ago
The mass of copper obtained experimentally was 0.872 g. Calculate the percentage yield of
frozen [14]

Answer:

% yield = (0.872 g Cu / 1.017 g ) x 100 = 85.74 %.

6 0
3 years ago
The iron with which they make the houses or bridges is the same as our blood?
Leviafan [203]

Explanation:

yes, they are the same.

"Iron is a mineral that the body needs for growth and development. Your body uses iron to make hemoglobin, a protein in red blood cells that carries oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles."

Fun fact:

At 4 grams per person, you'd need at least 2,352 completely drained donors to make a iron longsword out of blood.

3 0
3 years ago
If she suddenly dropped the books, this would increase their energy. If she instead decided to hold the books over her head, thi
Anna35 [415]

Answer:

the answer is is is true

7 0
3 years ago
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