All categories

3 years ago

The graph represents the decay curve of a radioactive isotope called strontium 90 what is the half life of this isotope

Chemistry

2 answers:

Nuetrik [128]3 years ago

6 0

I think the answer is *d*

IgorC [24]3 years ago

3 0

Yes i also think it is D

You might be interested in

Answer these questions based on 234. 04360 as the atomic mass of thorium-234. The masses for the subatomic particles are given.

nikdorinn [45]

The mass defect for the isotope thorium-234 if given mass is 234.04360 amu is 1.85864 amu.

<h3>How do we calculate atomic mass?</h3>

Atomic mass (A) of any atom will be calculated as:

A = mass of protons + mass of neutrons

In the Thorium-234:

Number of protons = 90

Number of neutrons = 144

Mass of one proton = 1.00728 amu

Mass of one neutron = 1.00866 amu

Mass of thorium-234 = 90(1.00728) + 144(1.00866)

Mass of thorium-234 = 90.6552 + 145.24704 = 235.90224 amu

Given mass of thorium-234 = 234.04360 amu

Mass defect = 235.90224 - 234.04360 = 1.85864 amu

Hence required value is 1.85864 amu.

To know more about Atomic mass (A), visit the below link:

brainly.com/question/801533

4 0

2 years ago

I am having some trouble figuring out how to approach the following problem: A 75.0-mL volume of 0.200 M NH3 (Kb=1.8×10−5) is ti

Tanya [424]

<span>We look at the end of the day:

n(HNO3) added = 0.500*17.0/1000 = 0.00850 mol
n(NH3) = 0.200*75.0/1000 - 0.00850 = 0.00650 mol
[NH3] left = 0.00650*1000/(17.0+75.0) = 0.070652
M [OH-] = Kb * [NH3] = 0.070652*1.8*10^(-5) = 1.27174 x 10^(-6)
pOH = -log[OH-] ≈ 5.8956 pH = 14 - pOH ≈ 8.10</span>

4 0

3 years ago

5. What concentration of acid must be added to change the pH of 1 mM phosphate buffer from 7.4 to 7.3 (pKas of the phosphate buf

mr_godi [17]

Explanation:

According to the Henderson-Hasselbalch equation, the relation between pH and $pK_{a}$ is as follows.

pH = $pK_{a} + log \frac{base}{acid}$

where, pH = 7.4 and $pK_{a}$ = 7.21

As here, we can use the $pK_{a}$ nearest to the desired pH.

So, 7.4 = 7.21 + $log \frac{base}{acid}$

0.19 = $log \frac{base}{acid}$

$\frac{base}{acid}$ = 1.55

1 mM phosphate buffer means $[HPO_{4}]$ + $[H_{2}PO_{4}]$ = 1 mM

Therefore, the two equations will be as follows.

$\frac{HPO_{4}}{H_{2}PO_{4}}$ = 1.55 ............. (1)

$[HPO_{4}]$ + $[H_{2}PO_{4}]$ = 1 mM ........... (2)

Now, putting the value of $[HPO_{4}]$ from equation (1) into equation (2) as follows.

1.55 $[H_{2}PO_{4}] + [tex][H_{2}PO_{4}]$ = 1 mM

2.55 $[H_{2}PO_{4}]$ = 1 mM

$[H_{2}PO_{4}]$ = 0.392 mM

Putting the value of $[H_{2}PO_{4}]$ in equation (1) we get the following.

0.392 mM + $[HPO_{4}]$ = 1 mM

$[HPO_{4}]$ = (1 - 0.392) mM

$[HPO_{4}]$ = 0.608 mM

Thus, we can conclude that concentration of the acid must be 0.608 mM.

7 0

3 years ago

The boiling points of different substances are given in the table below.

Oksi-84 [34.3K]

Answer:

Water

Explanation :-

Higher the intermolecular forces between the liquid particles, higher its boiling point.

8 0

4 years ago

From the dry desert of the south to the mountains of the north—Arizona has a varied topography. When residents of Phoenix visit

dedylja [7]

Answer:

The reason is because Flagstaff is at a higher elevation than Phoenix.

Explanation:

The air is thinner at higher elevations. You can google Flagstaff's elevation compared to Phoenix but the simple answer is that air is thinner at higher elevations and some people used to 'thicker' air find it harder to breath, especially after some strenuous exercise.

6 0

3 years ago