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
Solnce55 [7]
2 years ago
13

Doctors have fought infections with penicillin for over 50 years. Recently, penicillin has not worked as well as before. Which o

f the following explanations can account for this observation? A. Some bacteria are resistant to the drug. The continued use of the drug has killed all of these bacteria. B. Penicillin use has made all bacteria resistant to it. C. Some bacteria are resistant to penicillin. The continued use of the drug has killed all but these bacteria. D. Bacteria eat penicillin, so it is not effective anymore.
Chemistry
1 answer:
Lilit [14]2 years ago
5 0

C. "A" mentions that the drug killed all of the bacteria that are resistant to the drug, and that doesn't make any sense. "B" claims that all bacteria are resistant to the drug. This is not true. "D" mentions that bacteria eat the drug, which doesn't happen.

You might be interested in
One mole of ANY element contains the:
VMariaS [17]

Answer:

1)The molar mass of an atom is simply the mass of one mole of identical atoms. However, most of the chemical elements are found on earth not as one isotope but as a mixture of isotopes, so the atoms of one element do not all have the same mass.

2)Equally important is the fact that one mole of a substance has a mass in grams numerically equal to the formula weight of that substance. Thus, one mole of an element has a mass in grams equal to the atomic weight of that element and contains 6.02 X 1023 atoms of the element.

3 0
2 years ago
Read 2 more answers
If 1 mol of XO₂ contains the same number of atoms as 60 g of XOs, what is the molar mass of XO₂?
Lena [83]

Answer:

44 grams/mole

Explanation:

<u>If 1 mol of XO₂ contains the same number of atoms as 60 g of XO3, what is the molar mass of XO₂?</u>

<u></u>

60 grams of XO3 is one mole XO3, since it has the same number of atoms as 1 mole of XO2.

Let c be the molar mass of X.  The molar mass of XO3 is comprised of:

X:  c

3O:  3 x 16 = 48

Total molar mass of XO3 is = <u>48 + c</u>

We know that the molar mass of XO3 = 60 g/mole, so:

48 + c  = 60 g/mole

c = 12 g/mole

The molar mass of XO2 would be:

1 X = 12

2 O = 32

Molar mass = 44 grams/mole, same as carbon dioxide.  Carbon's molar mass is 12 grams.

<u></u>

<u></u>

5 0
2 years ago
Which best describes the relationship between the terms frequency, wavelength, and hertz?
Oksanka [162]

Answer:

The correct answer is - Frequency is the number of wavelengths, which is measured in hertz.

Explanation:

Frequency is the number of waves that go through a fixed point at a particular time. Hertz is the SI unit for frequency which means that one hertz is equal to a unit number of waver passes in a unit time to a fixed point.

As the frequency of a wave increases which means the number of waves increases in the unit time, the shorter the wavelength will be.

a higher frequency wave has more energy than a lower frequency wave with the same amplitude.

5 0
3 years ago
If we start with 8000 atoms of radium-226 how much would remain after 3200 years?
olya-2409 [2.1K]
<h3>Answer:</h3>

2000 atoms

<h3>Explanation:</h3>

We are given the following;

Initial number of atoms of radium-226 as 8000 atoms

Time taken for the decay 3200 years

We are required to determine the number of atoms that will remain after 3200 years.

We need to know the half life of Radium

  • Half life is the time taken by a radio active material to decay by half of its initial amount.
  • Half life of Radium-226 is 1600 years
  • Therefore, using the formula;

Remaining amount = Original amount × 0.5^n

where n is the number of half lives

n = 3200 years ÷ 1600 years

 = 2

Therefore;

Remaining amount = 8000 atoms × 0.5^2

                                = 8000 × 0.25

                                 = 2000 atoms

Thus, the number of radium-226 that will remain after 3200 years is 2000 atoms.

6 0
3 years ago
Find the formula for the compound that contains 72.40% iron and 27.60% oxygen.
Vikki [24]
Oxygen = 16
Iron = 55.8
16 x 27.6% = 4.4 /4 = 1.1
55.8 x 72.4% = 40.4 /4 = 10.1
1 oxygen and 10 iron, so Fe10 O

8 0
3 years ago
Other questions:
  • Which property describes a material's ability to conduct heat?
    8·2 answers
  • Which of the following lists includes only molecules?
    6·1 answer
  • What is the hybridization of bromine in BrO2-?
    14·2 answers
  • Hc1 is the formula for .
    12·1 answer
  • (15 PTS) What are two parts of the atomic theory of atoms?
    11·2 answers
  • an element has an isotope with a mass of 203.973 amu and and abundance of 1.40%. another isotope has a mass of 205.9745 amu with
    10·1 answer
  • What is the maximum volume of a 0.788 M CaCl2 solution that can be prepared using 85.3 g CaCl2?
    11·1 answer
  • Which radio wave has a higher frequency and carries more energy?????
    6·1 answer
  • What is the molecular formula of each compound?<br> (c) Empirical formula HgCl (m = 5 472.1 g/mol)
    14·1 answer
  • What is Racemic mixture?​
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!