Explanation:
The given data is as follows.
= 98.70 kPa = 98700 Pa,
T = 
= (30 + 273) K = 303 K
height (h) = 30 mm = 0.03 m (as 1 m = 100 mm)
Density = 13.534 g/mL = 
= 13534 
The relation between pressure and atmospheric pressure is as follows.
P = 
Putting the given values into the above formula as follows.
P =
= 
= 102683.05 Pa
= 102.68 kPa
thus, we can conclude that the pressure of the given methane gas is 102.68 kPa.
A titration is defined as 'the process of determining the quantity of a substance A by adding measured increments of substance B, the titrant, with which it reacts until exact chemical equivalence is achieved (the equivalence point)'.
The Molarity of the HCl Solution requires the addition of 24.6 mL of titrant is 0.0836 M (to 3 significant figures)
<h3>What is Titrant?</h3>
A reagent solution of precisely known concentration that is added in titration
Given reaction HCl + NaOH ===> NaCl + 
neutralization reaction
Note that the mole ratio is 1:1 meaning that 1 mole HCl reacts with 1 mole NaOH to produce 1 mole NaCl and 1 mole
Find moles of NaOH used:
18.45 ml x 1 L/1000 ml x 0.085 mol/L = 0.002091 moles NaOH used
This meant that there must be 0.002091 moles of HCl present in the 25.0 mls.
We want to find the molarity (M) which is moles HCl/liter of solution. We know the moles, and we also know the liters of solution (25.0 mls x 1 L / 1000 mls = 0.025 liters)
M = 0.002091 moles HCl / 0.025 liters = 0.08364 M = 0.0836 M (to 3 significant figures)
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It is defined as the amount of a substance that contains as many particles as there are atoms in 12 grams of pure carbon-12. So, 1 molecule contains 6.022×10^23 elementary entities of the substance.
Hope that helps
Enzymes that eventually break down the surface of bacteria are found in saliva, mucus, and tears, which act as chemical barriers against infection.
Enzymes found in saliva, mucous, as well as tears that degrade bacterial surfaces serve as chemical barriers preventing infection. The stomach's acid as well as the acid in sweat both destroy cellular pathogens, and even the semen contains antibacterial proteins.
There is no chemical and physical barrier offered by macrophages. Instead of acting as a barrier, macrophages target pathogens once they have already entered the body. Physical barriers include mucus as well as stratified squamous epithelium, whereas chemical barriers include saliva and urine.
Therefore, Enzymes that eventually break down the surface of bacteria are found in saliva, mucus, and tears, which act as chemical barriers against infection.
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Answer: C. ethanol
The enthalpy of combustion is the amount of heat produced when one mole of ethanol undergoes complete combustion at 25 ° C and 1 atmosphere pressure, yielding products also at 25 ° C and 1 atm.
<u>The enthalpy of combustion of the unknown compound is</u>
ΔH = - 320 kJ / 0.25 mol = - 1280 kJ / mol
<u>To choose a probable compound according to this combustion enthalpy, we must evaluate the deviation in relation to the values reported in the literature for the three probable compounds</u> (methane, ethylene and ethanol). The deviation (e%) will be calculated according to the following equation,
e% = ( | ΔHx - ΔH | / ΔHx ) x 100%
where ΔHx is the enthalpy of combustion of the probable compound.
The following table shows the combustion enthalpies of the probable compounds and their deviation in relation to the enthalpy of ΔH = - 1280 kJ / mol
Compound Enthalpy of combustion (kJ/mol) Deviation
Methane - 890.7 43.8%
Ehylene -1411.2 9.3%
Ethanol -1368.6 6.5%
According to the previous table, we can say that the most probable compound is ethanol, since it has the smallest deviation in relation to the experimental enthalpy value of combustion.
