Answer:
wavelength = 0.534×10⁻¹⁶ m
Explanation:
Given data:
Frequency of wave = 5.62 ×10²⁴ Hz
Wavelength = ?
Solution:
Speed of photon = wavelength × frequency
wavelength = speed of photon / frequency
Now we will put the values in formula:
wavelength = 3×10⁸ m/s / 5.62 ×10²⁴ Hz
Hz = s⁻¹
wavelength = 3×10⁸ m/s / 5.62 ×10²⁴ s⁻¹
wavelength = 0.534×10⁻¹⁶ m
The reaction is,
H2S + I2 --------------> 2 HI +S
Molar weight of H2S = 34 g per mol
Molar weight of HI =128 g per mol
Molar weight of I2 =254 g per mol
Moles of H2S in 49.2 g = 49.2 /34 mol = 1.447 mol
So according to stoichiometry of the reaction, number of I2 mols needed
= 1.447 mol
The mass of I2 needed = 1.447 mol x 254 g
The number 345,000 has 3 significant figures because the trailing zeros are not significant since there's no decimal point.
<h3>What is significant figures?</h3>
Significant figures of a number in positional notation are digits in the number that are reliable and necessary to indicate the quantity of something.
Also significant figures can be defined as, the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.
Examples of significant figures;
- 405 = 3 significant figures
- 405000 = 3 significant
- 0.040500 = 5 significant figures
<u>Note:</u> leading zeros are not significant but trailing zeros, which are zeros at the end of a number, are significant only if the number has a decimal point.
345,000 = 3.45 x 10⁵ (3 significant figures)
Thus, the number 345,000 has 3 significant figures because the trailing zeros are not significant since there's no decimal point.
Learn more about significant figures here: brainly.com/question/24491627
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Answer:
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Explanation:
The balanced chemical reaction to obtain water from SnO₂ is:
The mole ratio is:
Find the number of moles equivalent to 1.20× 10²¹ molecules of water, using Avogadro's number:
From the mole ratio, the number of moles of SnO₂ are half the number of moles of water. That is:
- 0.0019927 moles / 2 = 0.00099635 moles of SnO₂
Use the molar mass of SnO₂ to convert the number of moles to grams:
- molar mass of SnO₂ = 150.71g/mol
- mass of SnO₂ = 0.00099635mol × 150.71 g/mol = 0.150 grams.
The answer must be reported with 3 significant figures.
The half-life of any substance is the amount of time taken for half of the original quantity of the substance present to decay. The half-life of a radioactive substance is characteristic to itself, and it may be millions of years long or it may be just a few seconds.
In order to determine the half-life of a substance, we simply use:
t(1/2) = ln(2) / λ
Where λ is the decay constant for that specific isotope.
