Answer:

Explanation:
The question will be easier to solve if we interpret it as, " How long will it take until one-fourth of a sample of the element remains,?"
The half-life of the element is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:


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 answer is 2 more oxygen is needed
The correct answer among the choices given is option A. Hydrochloric acid is a much stronger acid than sulfuric acid given that the concentration both is equal. This can be proved by the pKa of these acids. Hydrochloric acid has a pKa of -6 while the pKa of sulfuric acid is -3. The lower the value of the pKa, the stronger the acidity of the substance.