Answer:

Explanation:
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In this case, since the percent water is computed by dividing the amount of water by the total mass of the hydrate; we infer we first need the molar mass of water and that of the hydrate as shown below:

Thus, the percent water is:

So we plug in to obtain:

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Answer:
1.00 × 10¹⁸
Explanation:
1. Calculate the <em>energy of one photon</em>
The formula for the energy of a photon is
<em>E</em> = <em>hc</em>/λ
<em>h</em> = 6.626 × 10⁻³⁴ J·s; <em>c</em> = 2.998 × 10⁸ m·s⁻¹
λ = 477 nm = 477 × 10⁻⁹ m Insert the values
<em>E</em> = (6.626 × 10⁻³⁴ × 2.998× 10⁸)/(477 × 10⁻⁹)
<em>E</em> = 4.165× 10⁻¹⁹ J
2. Calculate the <em>number of photons</em>
Divide the total energy by the energy of one photon.
No. of photons = 0.418 × 1/4.165 × 10⁻¹⁹
No. of photons = 1.00 × 10¹⁸
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Answer:
0.007 M
Explanation:
pH is defined as the negative logarithm of the concentration of hydrogen ions.
Thus,
pH = - log [H⁺]
The expression of the pH of the calculation of weak acid is:-
Where, C is the concentration = ?
Given, pH = 3.45
So, for
,

C = 0.007 M