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3 years ago

5

On the period table, the rows are called

1 answer:

liubo4ka [24]3 years ago

5 0

They’re called periods, answer A

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Sound wave a has lower frequency than sounds wave b but both waves have the same amplitude . What must also be true of these two

Nady [450]

Explanation:

Higher the frequency smaller will be the wavelength. Higher frequency have shorter wavelength and lower frequency waves have larger wavelength. Also, Beats are formed by the superposition of two waves with slightly different frequencies but with similar amplitudes. In time, waves switch between constructive interference and disruptive interference, giving the resultant wave a time-varying amplitude.

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3 years ago

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A student dissolved 1.805g of a monoacidic weak base in 55mL of water. Calculate the equilibrium pH for the weak monoacidic base

yawa3891 [41]

Answer:

11.39

Explanation:

Given that:

$pK_{b}=4.82$

$K_{b}=10^{-4.82}=1.5136\times 10^{-5}$

Given that:

Mass = 1.805 g

Molar mass = 82.0343 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{1.805\ g}{82.0343\ g/mol}$

$Moles= 0.022\ moles$

Given Volume = 55 mL = 0.055 L ( 1 mL = 0.001 L)

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Molarity=\frac{0.022}{0.055}$

Concentration = 0.4 M

Consider the ICE take for the dissociation of the base as:

B + H₂O ⇄ BH⁺ + OH⁻

At t=0 0.4 - -

At t =equilibrium (0.4-x) x x

The expression for dissociation constant is:

$K_{b}=\frac {\left [ BH^{+} \right ]\left [ {OH}^- \right ]}{[B]}$

$1.5136\times 10^{-5}=\frac {x^2}{0.4-x}$

x is very small, so (0.4 - x) ≅ 0.4

Solving for x, we get:

x = 2.4606×10⁻³ M

pOH = -log[OH⁻] = -log(2.4606×10⁻³) = 2.61

<u>pH = 14 - pOH = 14 - 2.61 = 11.39</u>

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2 years ago

The growth rate is the death rate minus the birth rate these change because birth rates and

zysi [14]

Answer:

Hey there!

False. The growth rate is actually the birth rate minus the death rates.

Let me know if this helps :)

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Describe ask a question in in sincence

Vadim26 [7]

Joke is that yur crazy

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Which part of the fuel cell does A represent?

Bad White [126]

I think the anwer is electrolyte :)... i had it on a test a couple days ago.

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