Answer:
<u>253.33 mmHg</u>
Explanation:
According to Charles' Law,
P₁ / T₁ = P₂ / T₂
P₁T₂ = P₂T₁
P₂ = P₁T₂ / T₁
= 760 x 40 / 30
= 760 x 4/3
= 1013.33 mmHg
Change in Pressure
= 1013.33 - 760
= <u>253.33 mmHg</u>
The primary difference between a hypothesis and a theory is that a hypothesis is falsifiable but a theory has been proven to be correct. An hypothesis is a proposed explanation put forward on the basis of limited evidence as a commencement point for further investigation, at the end of the investigation the theory may not be accepted if it failed to meet some criteria. A theory is a proven system of ideas used to explain a particular phenomenon.
Answer: -
15.55 M
35.325 molal
Explanation: -
Let the volume of the solution be 1000 mL.
Density of nitric acid = 1.42 g/ mL
Total Mass of nitric acid Solution = Volume of nitric acid x Density of nitric acid
= 1000 mL x 1.42 g/ mL
= 1420 g.
Percentage of HNO₃ = 69%
Amount of HNO₃ = 
= 979.8 g
Molar mass of HNO₃ = 1 x 1 + 14 x 1 + 16 x 3 = 63 g /mol
Number of moles of HNO₃ = 
= 15.55 mol
Molarity is defined as number of moles per 1000 mL
We had taken 1000 mL as volume and found it to contain 15.55 moles.
Molarity of HNO₃ = 15.55 M
Mass of water = Total mass of nitric acid solution - mass of nitric acid
= 1420 - 979.8
= 440.2 g
So we see that 440.2 g of water contains 15.55 moles of HNO₃
Molality is defined as number of moles of HNO₃ present per 1000 g of water.
Molality of HNO₃ = 
= 35.325 molal
Answer : The total number of atoms in the product are, 36 atoms.
Explanation :
Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.
When 1 molecule of glucose reacts completely with 3 molecules of oxygen then it react to give 6 molecules of carbon dioxide and 6 molecules of water.
The balanced chemical reaction will be:

There are 3 atoms in carbon dioxide and 3 atoms in water.
Total number of atoms in the product = 6(3) + 6(3) = 36 atoms
Thus, the total number of atoms in the product are, 36 atoms.
Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).