Answer: The percentage composition of hydrogen in the given compound is 15%.
Explanation:
To calculate the percentage composition of hydrogen in a compound, we use the formula:

Where,
Mass of hydrogen = 41.4 grams
Mass of compound = 276 grams
Putting values in above equation, we get:

Percentage composition of hydrogen in a given compound = 15%
The number of formula units in 2.50 mol of the compound is 15.1 * 10^23.
The question is unclear whether NaNO2 or NaNO3 is implied. However,in either case, the solution applies equally.
6.02 * 10^23 formula units of the compound are contained in 1 mole
x formula units are contained in 2.5 moles of the compound
x = 6.02 * 10^23 formula units * 2.5 moles/ 1 mole
x = 15.1 * 10^23 formula units of the compound.
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Answer: Temperature before the increase in
was a few degrees lower than temperature after the increase.
Explanation:
According to Charle's Law which states that The volume of gas is directly proportional to the temperature of the gas, when pressure is kept constant.

(At constant Pressure)
With the increase in level
in atmosphere the increase in temperature of the atmosphere will be observed.
Hence, temperature before the increase in
was a few degrees lower than temperature after the increase.
According to Henderson–Hasselbalch Equation,
pH = pKa + log [Acetate] / [Acetic Acid]
As,
pKa = -log Ka
pKa = -log (1.8 × 10⁻⁵)
pKa = 4.74
So,
pH = 4.74 + log [Acetate] / [Acetic Acid]
4.34 = 4.74 + log [Acetate] / [Acetic Acid]
4.34 - 4.74 = log [Acetate] / [Acetic Acid]
-0.40 = log [Acetate] / [Acetic Acid]
Taking Antilog on both sides,
[Acetate] / [Acetic Acid] = 0.398