Answer:
air that moves from high pressure to low pressure
Answer : The enthalpy of the reaction is, -2552 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given enthalpy of reaction is,

The intermediate balanced chemical reactions are:
(1)

(2)

(3)

(4)

Now we have to revere the reactions 1 and multiple by 2, revere the reactions 3, 4 and multiple by 2 and multiply the reaction 2 by 2 and then adding all the equations, we get :
(when we are reversing the reaction then the sign of the enthalpy change will be change.)
The expression for enthalpy of the reaction will be,



Therefore, the enthalpy of the reaction is, -2552 kJ/mole
Assume 1 tsp is approximately can hold 5 mL liquid.
Given the dose of medicine = 1.5 tsp
Converting 1.5 tsp to mL:
= 7.5 mL
Given the specific gravity of the medicine = 1.23
That means density of the medicine with respect to water will be 1.23
As the density of water is 1 g/mL
We can take density of the medicine to be 1.23 g/mL
Calculating the mass of medicine in grams:

9.225 g medicine is present in one dose.
Answer:
3.91 minutes
Explanation:
Given that:
Biacetyl breakdown with a half life of 9.0 min after undergoing first-order reaction;
As we known that the half-life for first order is:

where;
k = constant
The formula can be re-written as:



Let the initial amount of butter flavor in the food be
= 100%
Also, the amount of butter flavor retained at 200°C
= 74%
The rate constant 
To determine how long can the food be heated at this temperature and retain 74% of its buttery flavor; we use the formula:


Substituting our values; we have:

t = 3.91 minutes
∵ The time needed for the food to be heated at this temperature and retain 74% of its buttery flavor is 3.91 minutes
It's C, the amount of protons in the nucleus of each atom :)