3 elements are present in HCOOH - hydrogen, oxygen, and carbon.
Total vapor pressure can be calculated using partial vapor pressures and mole fraction as follows:

Here,
is mole fraction of A,
is mole fraction of B,
is partial pressure of A and
is partial pressure of B.
The mole fraction of A and B are related to each other as follows:

In this problem, A is hexane and B is octane, mole fraction of hexane is given 0.580 thus, mole fraction of octane can be calculated as follows:

Partial pressure of hexane and octane is given 183 mmHg and 59.2 mmHg respectively.
Now, vapor pressure can be calculated as follows:

Putting the values,

Therefore, total vapor pressure over the solution of hexane and octane is 131 mmHg.
Scientists can measure the height in
different units but problem could arise when they compare all the measurements.
That is the reason there is standard units for measurements.
<span>There may be error arises when an
American scientist is measuring the height of an object in inches and other Australian
scientist is measuring the height of same object in meters. Their data cannot
be compared because they are using different units to measure height.</span>
Answer:
The answer to your question is It will be formed 0.39 moles of H₂
Explanation:
Data
moles of H₂ = ?
moles of HCl = 0.78
moles of Zinc = excess
Balanced chemical reaction
2 HCl + Zn ⇒ 1 H₂ + ZnCl₂
Process
1.- Use proportions to solve this problem. Consider the coefficients of the balanced reaction.
2 moles of HCl ---------------------- 1 mol of H₂
0.78 moles of HCl ----------------- x
x = (0.78 x 1) / 2
- Simplification
x = 0.78 / 2
- Result
x = 0.39 moles of H₂