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AleksAgata [21]
3 years ago
8

The reason for the dramatic decline in the number of measles cases from the 1960s to 2010 in the United States was because the v

accine
Chemistry
1 answer:
Firlakuza [10]3 years ago
5 0

Answer:

It was because the vaccine generated actively acquired immunity, that is, inoculation of a portion of the measles virus so that the body forms the antibodies for a second contact and thus can destroy it without triggering the pathology.

Explanation:

Vaccines are methods of active acquired immunity since the antibody is not passively inoculated, it is manufactured by the body with a physiological process once part of the virus is inoculated.

The measles virus most of all affected the lives of infants or newborn children with severe rashes and high fevers that led to death.

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A sample of sugar (C12H22O11) contains 1.505 × 1023 molecules of sugar. How many moles of sugar are present in the sample?
saveliy_v [14]

Answer: Option (a) is correct.

Explanation:

Molecules of sugar given = 1.505 \times 10^{23}

According to Avogadro's number it is known that 1 mole contains 6.023 \times 10^{23}.

Therefore, calculate the moles of sugar present in the sample as follows.

   Number of moles =  \frac {1.505 \times 10^{23}}{6.023 \times 10^{23}}

           = 0.25 mol

Thus, the moles of sugar present in the sample is 0.25 mol.

6 0
3 years ago
Read 2 more answers
Na+H2O=NaOH+H2<br> Balancing
elena55 [62]

Answer:

Hey mate, here is your answer. Hope it helps you.

Explanation:

The balanced equation is 2Na+2H2O———-> 2NaOH +H2.

6 0
3 years ago
Place the steps of the action potential in order.
Ierofanga [76]

Answer:

-Reversal of the resting potential due to influx of sodium ions

-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations

-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability

-A brief reversal of membrane potential that travels along the axon

Explanation:

An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV

There are three steps of the moving action potential, including;

1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron

2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell

3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential

4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon

7 0
3 years ago
A 360. mg sample of aspirin, C9H8O4, (molar mass 180. g), is dissolved in enough water to produce 200. mL of solution. What is t
Gemiola [76]

Answer:

Molarity = 0.01 M

Explanation:

Molarity is used to measure the concentration of a solution. It will be same for the whole solution or a small amount of solution if the solution is homogeneous.

So, <u>Molarity of 200 mL of solution = Molarity of 50 mL of solution</u>

\mathbf{Molarity = \frac{number \ of \ moles \ of \ solute}{Volume \ of \ solution \ (in \ liters)}}

\mathbf{Moles = \frac{given \ mass \ of \ compound}{molar \ mass \ of \ compound}}

given mass of aspirin = 360 mg = 0.36 g

molar mass of aspirin = 180 g

Volume of solution = 200 mL = 0.2 L

\mathrm{Mole \ of \ Aspirin = \frac{0.36}{180} = \mathbf{0.002 \ moles}}

\mathrm{Molarity = \frac{0.002}{0.2} = \mathbf{0.01 \ M}}

Therefore, Molarity = 0.01 M

7 0
3 years ago
Please help I’m timed !!!
Rashid [163]

Answer:

b. \% diss =4.4x10^{-2}\%

Explanation:

Hello there!

In this case, given the ionization reaction of HClO as weak acid:

HClO\rightleftharpoons H^++ClO^-

We can write the equilibrium expression as shown below:

Ka=3.5x10^{-8}=\frac{[H^+][ClO^-]}{[HClO]}

In such a way, via the definition of x as the reaction extent, we can write:

3.5x10^{-8}=\frac{x^2}{[HClO]}

As long as Ka<<<<1 so that the x on the bottom can be neglected. Thus, we solve for x as shown below:

x=\sqrt{3.5x10^{-8}*0.18} =\\\\x=7.94x10^{-5}M

And finally the percent dissociation:

\% diss=\frac{x}{[HClO]} *100\%\\\\\% diss=\frac{7.94x10^{-5}M}{0.18}*100\% \\\\\% diss =0.044\%=4.4x10^{-2}\%

Which is choice b.

Best regards!

6 0
3 years ago
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