Answer:
Explanation:
Given parameters:
Number of given calories = 614 cal
Note that 1cal = 4.18J
Now to convert the given calories to joule, we use the relationship below:
Since 1Cal gives 4.18Joule of energy
614Cal will produce 4.18 x 614;
2566.52J of energy.
This written as 2.57 x 10³J because it has three significant numbers of 2, 5 and 7.
In writing an operation that involves deducing the significant numbers, we simply express our answer to that shows the lowest number of significant numbers. Our problem has 3 significant numbers each and the answer is given in that regard.
kg and all the given units are units used to measure mass.
kg is the standard unit to measure mass
lets find the value of 0.00684 kg in all the given units
a. dkg
1 kg is equivalent to 100 decagram (dkg)
therefore 0.00684 kg is = 100 dkg/kg x 0.00684 kg = 0.684 dkg
this is not the given value therefore this choice is incorrect
b. 1 kg is equivalent to 1000 g
therefore 0.00684 kg = 1000 g/kg x 0.00684 kg = 6.84 g
this is the given value so this is correct
c. 1 kg is equivalent to 100 000 centigrams (cg)
therefore 0.00684 kg = 100 000 cg/kg x 0.00684 kg = 684 cg
this is the given value so this is also correct
d) 1 kg is equivalent to 1 000 000 mg
therefore 0.00684 kg = 1 000 000 mg/kg x 0.00684 kg = 6 840 mg
this too is correct
the incorrect answer is A. 0.0684 dkg
Answer:
439.7nm
Explanation:
Energy of a quantum can be calculated using below formula
E=hv...........eqn(1)
But v=λ/ c .........eqn(2)
If we substitute eqn(2) into eqn(1) we have
E= hc/(λ)
Where E= energy
h= Plank's constant= 6.62607004 × 10-34 m2 kg / s
c= speed of light
c= 2.998 × 10^8 m/s
λ= wavelength= ?
But the energy was given in Kj , it must be converted to Kj/ photon for unit consistency.
Energy E= 272 kJ/mol × 1mol/6.02× 10^23
Energy= 451.83× 10^-24 Kj/ photon
E= hc/(λ)...........eqn(1)
If we make λ subject of the formula
λ= hc/E
Then substitute the values we have
λ= [(6.626 × 10^-34) × (2.998 × 10^8)]/451.83× 10^-24
λ=(0.00043965) × (1Kj/1000J) × (10^9nm/1m)
λ=439.7nm
Hence, the longest wavelength of radiation with enough energy to break carbon-sulfur bonds is 439.7nm
1mol=6.022x10^23 atoms
3.75mol= 6.022x3.75x10^23 atoms
=2.2583x10^24 atoms
