Answer:
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Explanation:
The molarity of Sr(OH)2 solution is = 0.1159 M
calculation
write the equation for reaction
that is, Sr(OH)2 +2HCl→ SrCl2 + 2 H2O
then finds the mole of HCl used
moles = molarity x volume
=40.03 x0.1159 = 4.639 moles
by use of mole ratio between Sr(OH)2 to HCL which is 1 :2 the moles of Sr(OH)2 is therefore = 4.639 x1/2 = 2.312 moles
molarity of Sr(OH)2 is = moles / volume
=2.312 /20 =0.1159 M
M(C2H2O)= 12.0*2 +1.0*2 +16.0 = 42 g/mol is a molar mass for empirical formula.
120.6g/mol/42g/mol ≈ 3
So, empirical formula should be increased 3 times,
and molecular formula is C6H6O3.
Answer is D.
Number of photons can be calculated by dividing the needed energy by the energy per photon.
The minimum energy needed is given as 2 x 10^-17 joules
Energy per photon = hc / lambda where h is planck's constant, c is the speed of light and lambda is the wavelength
Energy per photon = (<span>6.626 x 10^-34 x 3 x 10^8) / (475 x 10^-9)
= 4.18 x 10^-19 J
number of photons = (2 x 10^-17) / (4.18 x 10^-19)
= 47.79 photons which is approximately 48 photons</span>
