Answer:
The response is identical to 9.11x10-31kg, which refers to electron mass.
Explanation:
The mass of an electron written in scientific notation is 9.11x10-31, which translates to 0.000000000000000000000000000000911 in standard form. While the former is more compact and easily interpretable, the latter appears cumbersome.
When discussing three significant figures, it indicates three non-zero digits. Essentially, your answer should use three digits that are not zero, starting with the first digit as non-zero, which in this case is "nine" - "9", followed by "1" and "1" as the two additional significant figures.
The amount to administer to the child is 2,469 mL.
To convert to kilograms (kg), the child's weight in pounds (lb) is multiplied by 0.45359237: m(child) = 72.6 · 0.045359237 = 32.93 kg.
To find m(Medrol), the child's mass in kilograms is multiplied by 1.5 mg/kg.
Thus, m(Medrol) = 32.93 kg · 1.5 mg/kg = 49.39 mg.
The concentration of Medrol is d(Medrol) = 20.0 mg/mL.
To find the volume of Medrol needed, use V(Medrol) = m(Medrol) ÷ d(Medrol).
So, V(Medrol) = 49.39 mg ÷ 20 mg/mL = 2,469 mL.
Answer: second option: 1.70 to 1.40
Explanation:
1) pH is defined using the formula pH = - log [H₃O⁺]
2) Given that the initial concentration is x and after doubling it becomes 2x, we calculate:
pHi = - logx
pHf = - log 2x = - log 2 - logx
Thus, pHf - pHi = - log2 - logx - (- logx) = - log2 ≈ - 0.30
⇒ pHi - pHf = 0.30, indicating that the final pH (with twice the hydronium ions) is 0.30 lower than the starting pH.
3) The only option that indicates a 0.30 decline in pH is the second one: from 1.70 to 1.40. Therefore, that is the correct choice.
