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
jok3333 [9.3K]
2 years ago
7

What percentage of a substance remains after 7 half-lives have passed?

Chemistry
1 answer:
Mila [183]2 years ago
5 0

Answer:

Not really sure, buts its either B or C.

You might be interested in
A particular laser consumes 130.0 Watts of electrical power and produces a stream of 2.67×1019 1017 nm photons per second.
solniwko [45]

The missing question is:

<em>What is the percent efficiency of the laser in converting electrical power to light?</em>

The percent efficiency of the laser that consumes 130.0 Watt of electrical power and produces a stream of 2.67 × 10¹⁹ 1017 nm photons per second, is 1.34%.

A particular laser consumes 130.0 Watt (P) of electrical power. The energy input (Ei) in 1 second (t) is:

Ei = P \times t = 130.0 J/s \times 1 s = 130.0 J

The laser produced photons with a wavelength (λ) of 1017 nm. We can calculate the energy (E) of each photon using the Planck-Einstein's relation.

E = \frac{h \times c }{\lambda }

where,

  • h: Planck's constant
  • c: speed of light

E = \frac{h \times c }{\lambda } = \frac{6.63 \times 10^{-34}J.s  \times 3.00 \times 10^{8} m/s }{1017 \times 10^{-9} m }= 6.52 \times 10^{-20} J

The energy of 1 photon is 6.52 × 10⁻²⁰ J. The energy of 2.67 × 10¹⁹ photons (Energy output = Eo) is:

\frac{6.52 \times 10^{-20} J}{photon} \times 2.67 \times 10^{19} photon = 1.74 J

The percent efficiency of the laser is the ratio of the energy output to the energy input, times 100.

Ef = \frac{Eo}{Ei} \times 100\% = \frac{1.74J}{130.0J} \times 100\% = 1.34\%

The percent efficiency of the laser that consumes 130.0 Watt of electrical power and produces a stream of 2.67 × 10¹⁹ 1017 nm photons per second, is 1.34%.

You can learn more about lasers here: brainly.com/question/4869798

8 0
3 years ago
How many white blood cells does a normal adult with 5 L of blood have?
Mashcka [7]
5 L = 6.0 * 10^10

I believe.
6 0
3 years ago
A sample of aluminum is placed in a 25-ml graduated cylinder containing 10.0 ml of water. the level of the water rises to 18.0 m
OLga [1]
To determine the mass of the sample, first find the volume difference after and before the aluminum was placed, the volume change is equal to the volume of the submerged object, in this case aluminum.

Then knowing volume of aluminum and the density of it, we can solve for the mass.

D = m/v

Dv = m

2.7 g/ml • 8 ml = 21.6 grams.
5 0
3 years ago
Read 2 more answers
You heat 51 grams of magnesium over a Bunsen burner for several minutes until it reacts with oxygen in the air. Then you weigh t
garik1379 [7]

Answer:

    The mass was there all along, it was just in the air. The weight of the oxygen from the air is not weighed in the beginning, only at the end as part of the product, making it seem like there is a total mass change.

8 0
3 years ago
What is Charles’s law? State the definition of the law in words. What are the assumptions of Charles’s law? Write mathematical e
Leviafan [203]

Answer:

The volume of a given mas of a gas is directly proportional to the temperature if the pressure remains constant

V is directly proportional to T

V=1/T

V=constant/T

Explanation:

4 0
3 years ago
Other questions:
  • How much potassium iodide (76.45% i ) should be consumed to meet the rda?
    14·1 answer
  • Someone plz help fast !!!!!!!!!!!!!!!!!!
    6·2 answers
  • Zinc is used as a coating for steel to protect the steel from environmental corrosion. If a piece of steel is submerged in an el
    5·1 answer
  • Two samples of carbon tetrachloride were decomposed into their constituent elements. One sample produced 32.4 g of carbon and 37
    5·1 answer
  • Which phrase correctly describes a Lewis dot structure for carbon?
    8·2 answers
  • Q1.What is the mass of 5 moles Of 1.Mg
    8·2 answers
  • What is the best name for this molecule? Explain your naming process.
    6·1 answer
  • What is the source of almost all energy on earth
    6·2 answers
  • Identify the missing particle in the following nuclear equation.
    6·1 answer
  • Match each form from energy with its description
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!