A sample of hydrogen gas is collected over water at 25°C. The vapor pressure of water at 25°C is 23.8 mmHg. If the total pressure is 523.8 mmHg, what is the partial pressure of the hydrogen?

Answer:

1) The correct answer is option C.

2) the correct answer is option C.

Explanation:

1) Molecular formula of glucose =

Number of carbon atoms in single molecule = 6

Number of carbon atoms in 3  molecule of glucose :

of carbon

There are 18 carbon atoms in the 3 molecules of glucose.

2) Homogeneous mixture is the mixture in which components are evenly distributed throughout the mixture. The shape and size of the particles are identical in the mixture.

Heterogeneous mixture is the mixtures in which component are unevenly distributed throughout the mixture. The shape and size of the particles are not identical in the mixture.

Air is the mixture of gases with 78% of nitrogen gas, 21% of oxygen gas and remaining 1 % are other gases. Air is a homogeneous mixture of different gases.

Where as water, oxygen , alcohol are pure substances.

Answer:

B

Explanation:

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Answer is: 3) H2O and HCl.

Polar molecules are water (H₂O) and hydrochloric acid (HCl).

Nonpolar molecules are carbon(IV) oxide (CO₂) and methane (CH₄).

Carbon(IV) oxide is nonpolar because CO₂ is linear molecule and the oxygen atoms are symmetrical (bond angles 180°).

Water is polar because of the bent shape of the molecule.

Hydrochloric acid has polar covalent chemical bond where hydrogen has oxidation umber +1  and chlorine oxidation number -1.

In molecule of methane (CH₄) all the atoms around the central element (carbon) are equivalent (four hydrogens) and it has a net dipole moment of 0 (vectors of dipole moments cancel each other, dipole moment is zero).

Answer:

2.2 °C/m

Explanation:

It seems the question is incomplete. However, this problem has been found in a web search, with values as follow:

" A certain substance X melts at a temperature of -9.9 °C. But if a 350 g sample of X is prepared with 31.8 g of urea (CH₄N₂O) dissolved in it, the sample is found to have a melting point of -13.2°C instead. Calculate the molal freezing point depression constant of X. Round your answer to 2 significant digits. "

So we use the formula for freezing point depression:

• ΔTf = Kf * m

In this case, ΔTf = 13.2 - 9.9 = 3.3°C

m is the molality (moles solute/kg solvent)

• 350 g X ⇒ 350/1000 = 0.35 kg X

• 31.8 g Urea ÷ 60 g/mol = 0.53 mol Urea

Molality = 0.53 / 0.35 = 1.51 m

So now we have all the required data to solve for Kf:

• ΔTf = Kf * m

• 3.3 °C = Kf * 1.51 m

• Kf = 2.2 °C/m