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Marina CMI [18]
3 years ago
6

a 160 milligram sample of a radioactive isotope decays to 10 kilograms in 12 years. what is the half life of this element

Chemistry
1 answer:
Shkiper50 [21]3 years ago
8 0

Answer:

3 years

Explanation:

Given data:

Initial amount of sample = 160 Kg

Amount left after 12 years = 10 Kg

Half life = ?

Solution:

at time zero = 160 Kg

1st half life = 160/2 = 80 kg

2nd half life = 80/2 = 40 kg

3rd half life = 40 / 2 = 20 kg

4th half life = 20 / 2 = 10 kg

Half life:

HL = elapsed time / half life

12 years / 4 = 3 years

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Suppose that you add 26.7 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f Kf of 5.12 oC/m. With the a
kiruha [24]

From the calculation, the molar mass of the solution is 141 g/mol.

<h3>What is the molar mass?</h3>

We know that;

ΔT = K m i

K = the freezing constant

m = molality of the solution

i = the Van't Hoft factor

The molality of the solution is obtained from;

m = ΔT/K i

m = 3.89/5.12 * 1

m = 0.76 m

Now;

0.76 =  26.7 /MM/0.250

0.76 = 26.7 /0.250MM

0.76 * 0.250MM =  26.7

MM= 26.7/0.76 * 0.250

MM = 141 g/mol

Learn more about molar mass:brainly.com/question/12127540?

#SPJ12

5 0
2 years ago
A 45.0-gram sample of copper metal was heated from 20.0°C to 100.0°C. Calculate the heat absorbed, in kJ, by the metal.
s2008m [1.1K]

Answer:

1.386 KJ

Explanation:

From the question given above, the following data were obtained:

Mass (M) of copper = 45 g

Initial temperature (T1) = 20.0°C

Final temperature (T2) = 100.0°C

Heat absorbed (Q) =..?

Next, we shall determine the change in temperature. This can be obtained as follow:

Initial temperature (T1) = 20.0°C

Final temperature (T2) = 100.0°C

Change in temperature (ΔT) =?

ΔT = T2 – T1

ΔT = 100 – 20

ΔT = 80 °C

Next, we shall determine the heat absorbed by the sample of copper as follow:

Mass (M) of copper = 45 g

Change in temperature (ΔT) = 80 °C

Specific heat capacity (C) of copper = 0.385 J/gºC

Heat absorbed (Q) =..?

Q = MCΔT

Q = 45 × 0.385 × 80

Q = 1386 J

Finally, we shall convert 1386 J to KJ. This can be obtained as follow:

1000 J = 1 KJ

Therefore,

1386 J = 1386 J × 1 KJ /1000 J

1386 J = 1.386 KJ

Thus, the heat absorbed by the sample of the sample of copper is 1.386 KJ.

5 0
3 years ago
Please help me!! 70 points!!
ICE Princess25 [194]
Do all substances dissolve in water? Kids explore the varying levels of solubility of common household substances in this fun-filled experiment!

Materials Needed:
4 clear, glass jars filled with plain tap water
Flour
Salt
Talcum or baby powder
Granulated sugar
Stirrer
Step 1: Help your child form a big question before starting the experiment.

Step 2: Make a hypothesis for each substance. Perhaps the salt will dissolve because your child has watched you dissolve salt or sugar in water when cooking. Maybe the baby powder will not dissolve because of its powdery texture. Help your child write down his or her predictions.

Step 3: Scoop a teaspoon of each substance in the jars, only adding one substance per jar. Stir it up!

Step 4: Observe whether or not each substance dissolves and record the findings!

Your child will likely note that that sugar and salt dissolve, while the flour will partially dissolve, and the baby powder will remain intact. The grainy crystals of the sugar and salt are easily dissolved in water, but the dry, powdery substances are likely to clump up or remain at the bottom of the jar.

As you can see, the scientific method is easy to work into your child’s scientific experiments. Not only does it increase your child’s scientific learning and critical thinking skills, but it sparks curiosity and motivates kids as they learn to ask questions and prove their ideas! Get started today with the above ideas, and bring the scientific method home to your child during your next exciting science experiment
7 0
3 years ago
Which elements are magnetic in the periodic table?
rosijanka [135]
METALS ARE MAGNETIC(and maybe metalloids)

3 0
3 years ago
Which of the following is true?
tresset_1 [31]

Answer:

B

Explanation:

The sun can be dangerous but it also helps our Earth in a lot of ways

4 0
3 years ago
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