1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
natta225 [31]
3 years ago
7

As part of her nuclear stress test, Simone starts to walk on the treadmill. When she reaches the maximum level, Paul injects a r

adioactive dye with201Tl with an activity of 72 MBq . The radiation emitted from areas of her heart is detected by a scanner and produces images of her heart muscle. After Simone rests for 3 h, Paul injects more dye with 201Tl and she is placed under the scanner again. A second set of images of her heart muscle at rest is taken. When Simone's doctor reviews her scans, he assures her that she had normal blood flow to her heart muscle, both at rest and under stress.
Part A
If the half-life of 201Tl is 3.0 days, what is its activity, in megabecquerels after 3.0 days?
Express the activity to two significant figures and include the appropriate units.

Part B
What is its activity in megabecquerels after 6.0 days?
Express the activity to two significant figures and include the appropriate units.
Chemistry
1 answer:
Naya [18.7K]3 years ago
3 0

Answer:

Part A: 36 MBq; Part B: 18 MBq

Explanation:

The half-life is the time it takes for half the substance to disappear.

The activity decreases by half every half-life

A =Ao(½)^n, where n is the number of half-lives.

Part A

3.0 da = 1 half-life

A =  Ao(½) = ½ × 72 MBq = 36 MBq

Part B

6.0 da = 2 half-lives

A = Ao(½)^2 = ¼ × 72 MBq = 18 MBq

You might be interested in
The The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k=0.029 W/ m measured temperature differ
vfiekz [6]

Answer:

Heat flux = 13.92 W/m2

Rate of heat transfer throug the 3m x 3m sheet = 125.28 W

The thermal resistance of the 3x3m sheet is 0.0958 K/W

Explanation:

The rate of heat transfer through a 3m x 3m sheet of insulation can be calculated as:

q=-k*A*\frac{\Delta T}{\Delta X}\\\\q=-0.029\frac{W}{m*K}*(3m*3m)*\frac{12K}{0.025m}  =125.28W

The heat flux can be defined as the amount of heat flow by unit of area.

Using the previous calculation, we can estimate the heat flux:

heat \, flux=\frac{q}{A}=\frac{125.28 W}{9 m^{2} }  =13.92 W/m^{2}

It can also be calculated as:

q/A=-k*\frac{\Delta T}{\Delta X}

The thermal resistance can be expressed as

\Delta T=R_t*Q\\R_t=\Delta T/Q=\frac{\Delta X}{k*A}

For the 3m x 3m sheet, the thermal resistance is

R_t = \frac{\Delta X}{k*A}=\frac{0.025m}{0.029W/mK*9m^{2}}=0.0958 \, K/W

4 0
3 years ago
Isoelectric point. The isoelectric point (pI) is the pH at which a molecule has no net charge. The amino acid glycine has two io
timama [110]

Answer:

pI = 6.16

Explanation:

The pI is given by the average of the pKas that are involved. In this case,

Pka of carboxylic acid was given as 2.72 and that of the Amino group was given as 9.60. the average would then be ½(2.72+9.60)

= 6.16

6 0
3 years ago
Which organelle in the table is correctly matched with its function?<br> which one is it??
Papessa [141]

Answer:

\huge\boxed{\sf Ribosomes}

Explanation:

<h3>Organelles and their function:</h3><h3><u>Lysosomes:</u></h3>
  • Lysosomes functions in the digestion of food of the cell.
  • It contains hydrolytic enzymes.
<h3><u>Vacuole:</u></h3>
  • Vacuole mostly functions in storage.
<h3><u>Mitochondrion:</u></h3>
  • Mitochondrion is the power house of the cell.
<h3><u>Ribosome:</u></h3>
  • Ribosome functions in protein synthesis.

\rule[225]{225}{2}

4 0
1 year ago
400cm³ of dry air was passed over heated copper powder in a hard glass tube until no further change. What volume of remained at
Delicious77 [7]

Explanation:

I think there' will be a decrease in volume of the air.

3 0
2 years ago
Read 2 more answers
54.56 g of water at 80.4 oC is added to a calorimeter that contains 47.24 g of water at 40 oC. If the final temperature of the s
fomenos

Answer:

49.5J/°C

Explanation:

The hot water lost some energy that is gained for cold water and the calorimeter.

The equation is:

Q(Hot water) = Q(Cold water) + Q(Calorimeter)

<em>Where:</em>

Q(Hot water) = S*m*ΔT = 4.184J/g°C*54.56g*(80.4°C-59.4°C) = 4794J

Q(Cold water) = S*m*ΔT = 4.184J/g°C*47.24g*(59.4°C-40°C) = 3834J

That means the heat gained by the calorimeter is

Q(Calorimeter) = 4794J - 3834J = 960J

The calorimeter constant is the heat gained per °C. The change in temperature of the calorimeter is:

59.4°C-40°C = 19.4°C

And calorimeter constant is:

960J/19.4°C =

<h3>49.5J/°C</h3>

<em />

7 0
2 years ago
Other questions:
  • How to write a balanced chemical equation from empirical formula?
    5·1 answer
  • A typical aspirin tablet contains 5.00 grains of pure aspirin analgesic compound. The rest of the tablet is
    6·1 answer
  • In the explosion of a hydrogen-filled balloon, 0.40 g of hydrogen reacted with 3.2 g of oxygen. How many grams of water vapor ar
    15·1 answer
  • How do forensic scientist determine what exactly everything is
    5·2 answers
  • What is the SI unit used to measure the temperature of a substance?
    9·1 answer
  • The molecular weight of table salt, NaCl, is 58.5 g/mol. A tablespoon of salt weighs 6.37 grams. Calculate the number of moles o
    8·1 answer
  • Which statement regarding this equation is TRUE?
    9·1 answer
  • Chemistry question please help
    9·1 answer
  • What elements are most commonly used in wiring?
    15·1 answer
  • How many moles are in 1.23 X 1050 atoms of calcium carbonate, CaCO3?
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!