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VladimirAG [237]
2 years ago
14

I need help with Number 63

Chemistry
1 answer:
Lubov Fominskaja [6]2 years ago
8 0
Isotopes are variants of an element which have differing number of neutrons. So, yes, because all of them have the same atomic number, meaning they are all Mg, however they all have differing atomic masses meaning different number of neutrons.
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Since the half-life of 235U (7. 13 x 108 years) is less than that of 238U (4.51 x 109 years), the isotopic abundance of 235U has
Ymorist [56]

Answer:

\mathtt{ t_1-t_2= In(\dfrac{3}{y}) \times \dfrac{7.13 \times 10^8}{In2} \ years}

Explanation:

Given that:

The Half-life of ^{235}U = 7.13 \times 10^8 \ years is less than that of ^{238} U = 4.51 \times 10^9 \ years

Although we are not given any value about the present weight of ^{235}U.

So, consider the present weight in the percentage of ^{235}U to be  y%

Then, the time elapsed to get the present weight of ^{235}U = t_1

Therefore;

N_1 = N_o e^{-\lambda \ t_1}

here;

N_1 = Number of radioactive atoms relating to the weight of y of ^{235}U

Thus:

In( \dfrac{N_1}{N_o}) = - \lambda t_1

In( \dfrac{N_o}{N_1}) =  \lambda t_1 --- (1)

However, Suppose the time elapsed from the initial stage to arrive at the weight of the percentage of ^{235}U to be = t_2

Then:

In( \dfrac{N_o}{N_2}) =  \lambda t_2  ---- (2)

here;

N_2 =  Number of radioactive atoms of ^{235}U relating to 3.0 a/o weight

Now, equating  equation (1) and (2) together, we have:

In( \dfrac{N_o}{N_1}) -In( \dfrac{N_o}{N_2}) =  \lambda( t_1-t_2)

replacing the half-life of ^{235}U = 7.13 \times 10^8 \ years

In( \dfrac{N_2}{N_1})  = \dfrac{In 2}{7.13 \times 10^9}( t_1-t_2)      ( since \lambda = \dfrac{In 2}{t_{1/2}} )

∴

\mathtt{In(\dfrac{3}{y}) \times \dfrac{7.13 \times 10^8}{In2}= t_1-t_2}

The time elapsed signifies how long the isotopic abundance of 235U equal to 3.0 a/o

Thus, The time elapsed is  \mathtt{ t_1-t_2= In(\dfrac{3}{y}) \times \dfrac{7.13 \times 10^8}{In2} \ years}

8 0
3 years ago
Tear off a small, flat sheet of waxed paper. Use the pipette to dispense a drop of water on the waxed paper. Now, dry the pipett
Vilka [71]

Answer:

Explanation:

When comparing the drops of oil and water, one thing I noticed was the shape. The water drop was more defined, whereas the drop of oil began to spread and was much flatter. This may be due to the waxy material, and how both oil and water react to the wax.

7 0
2 years ago
How do you use the changes in the phase of water to keep you cool?
sineoko [7]

Answer:

by freezing

Explanation:

8 0
3 years ago
If the container is closed and the ethanol is allowed to reach equilibrium with its vapor, how many grams of liquid ethanol rema
SVETLANKA909090 [29]

Explanation:

Let us assume that the given data is as follows.

        V = 3.10 L,        T = 19^{o}C = (19 + 273)K = 292 K

       P = 40 torr    (1 atm = 760 torr)

So,     P = \frac{40 torr}{760 torr} \times 1 atm

             = 0.053 atm

          n = ?

According to the ideal gas equation, PV = nRT.

Putting the given values into the above equation to calculate the value of n as follows.

                 PV = nRT

   0.053 atm \times 3.10 L = n \times 0.0821 L atm/mol K \times 292 K

                 0.1643 = n \times 23.97

                    n = 6.85 \times 10^{-3}

It is known that molar mass of ethanol is 46 g/mol. Hence, calculate its mass as follows.

               No. of moles = \frac{mass}{\text{molar mass}}

                 6.85 \times 10^{-3} = \frac{mass}{46 g/mol}  

                    mass = 315.1 \times 10^{-3} g

                              = 0.315 g

Thus, we can conclude that the mass of liquid ethanol is 0.315 g.

4 0
3 years ago
Nitrous oxide (n2o), or laughing gas, is commonly used as an anesthetic in dentistry and surgery. how many moles are present in
Gelneren [198K]

Answer is: 0.375 moles are present in 8.4 liters of nitrous oxide at stp.

V(N₂O) = 8.4 L.

V(N₂O) = n(N₂O) · Vm.

Vm = 22,4 L/mol.<span>
n</span>(N₂O) = V(N₂O) ÷ Vm.

n(N₂O) = 8.4 L ÷ 22.4 L/mol.

n(N₂O) = 0.375 mol.<span>
Vm - molare volume on STP.</span>

5 0
3 years ago
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