This is solved using the ideal gas law. However, it should be recognized that 1 mol of any gas at 1 atm and 273K (or 0 deg Celsius) is approximately 22.4 L in volume. If this is not recognized, it can still be calculated from the ideal gas law, PV = nRT. We recognize that if pressure doubles while temperature and mols remain the same, the volume should be halved. Thus, the new volume is 11.2 L, which is a difference of 11.2 liters, or answer C.

The electron weighs 1/1833 of the mass of a proton and so contributes even less than 1/1000 of the mass of an atom.

This question is basically asking for a definition. A helium nucleus is called an alpha particle.

Generally, elements closer to fluorine in the periodic table have larger electronegativities.

Silver bromide is insoluble, whereas all other substances in the reaction are soluble. The ammonium ions and nitrate ions are spectator ions that cancel. Silver ions will form a complex with ammonia, NH₃, not with ammonium ions, NH₄⁺.

To determine the molar mass, the molarity equation will be needed.

Molarity = (moles of solute)/(Liters of solution)

Plugging in the values from the problem results in:

0.65 = (moles of solute)/(.302 L)

Note: The amount of the solution is given in terms of grams of water, this can be converted to mL by using the density of water (1.0 grams/mL) and then converting the mL into liters. Cross-multiplying gives the following:

0.65(.302) = moles of solute

The molar mass of a compound is in grams per mole. Therefore the molar mass of the unknown solute would be 45.1 grams of solute (from the question) divided by the number of moles just calculated 0.65(.302). Putting the pieces together results in a molar mass of the unknown solute of:

(45.1 grams)/0.65(.302)moles

We know that heat must be added to melt solids. Therefore the enthalpy must be positive. We can also readily visualize that the molecules in a solid are much more ordered and closer together than those in a liquid. Therefore the entropy change must be positive also.

In the periodic table sulfur is closest to fluorine and is expected to have the greatest electronegativity. Also, in general, metals tend to have lower electronegativities than nonmetals.

Buffers are prepared from a weak acid and its conjugate base or from a weak base and its conjugate acid. (A) NaCl and HCl; this pair has HCl which is a strong acid. (B) HC₂H₃O₂ and KC₂H₃O₂; this pair has a weak acid and its conjugate base (the C₂H₃O₂^- ion). (C) NaBr and KBr; this pair has no weak acid or base. (D) HIO₃ and KClO₃; this pair does not have a conjugate acid-base pair.

We set up the problem with the desired ratio to the left of the equal sign. To the right of the equal sign replace the given mass of metal in the numerator and the volume of H₂ in mL in the denominator. Since we already know the value of the final numerator, we just need to convert the denominator into moles of HCl.

Notice that we used the molar volume of an ideal gas at STP to convert the H₂ from mL to moles. Then we used the mole ratio that relates H₂ and HCl for the second conversion factor.

The SO₃ molecule has three resonance structures. Each has one oxygen drawn with a double bond to the sulfur and the other two oxygens drawn with a single bond to the sulfur. The remaining compounds have only one possible Lewis structure.

This is an example of an ionic compound. For every 1 iron atom, 2 sulfate ions are needed. If sulfate has a charge of -2 and 2 sulfates are present, then this results in a charge of -4. Since the ionic compound in the question is neutral, there should not be a charge left on the compound. Therefore, if sulfate has a -4 (is looking to gain 4 electrons), then the iron must have a +4 charge (be willing to transfer 4 electrons).

Decane is nonpolar, and propanol is polar and forms hydrogen bonds. Their polarities are very different, and they are not expected to be miscible. All other pairs have similar polarities and therefore should mix readily.

Standard temperature is defined as zero degrees Celsius when it comes to the gas laws. The standard pressure is one atmosphere of pressure that is also 760 torr (mm Hg).

Because the reaction rate increases by the same factor as the concentration of A, the reaction with respect to reactant A must be first order.

We expect elements with atomic numbers greater than 83 to be radioactive. Americium is the only one given that fulfills that criterion.

The question is ?g cholesterol = 1 molecule cholesterol

The important conversion factors in this problem are the number of grams per mole and the number of molecules per mole of cholesterol.

We know that energy and wavelength are inversely proportional to each other. The lowest energy radiation listed is infrared, and the highest energy is the X-ray. Therefore, their wavelengths go from high to low.

To determine the molecular formula using an empirical formula, the ratio of the molecular mass to the empirical mass must be calculated. Dividing the molecular mass of 128 grams by the empirical mass of ~16 grams (C = 12g + H = 1g, but there are 4 hydrogens in the compound) gives you approximately 8. This indicates that the empirical subscripts must be multiplied by 8 to result in the molecular formula of the unknown compound, C8H32.

None of the four answers fits. The positive free energy indicates a non-spontaneous system with more reactants than products. The large exothermic heat of reaction and the large increase in entropy are very unlikely with a large positive free energy.

In the equation, carbon is used from carbon dioxide to form glucose, C6H12O6. The final form of carbon is in glucose. In this compound, the oxygens each have an oxidation number of -2 and the hydrogen also have a fixed oxidation number of +1 each. Therefore, the sum of hydrogen’s oxidation numbers is +12 and the sum of oxygen’s oxidation numbers is -12. Since glucose is a neutral compound the sum of all the oxidation numbers of all the elements in the compound must be equal to zero. So, carbon must have an oxidation number of 0 because the sum of the hydrogen and oxygen oxidation numbers is already equal to zero.

A 3D network lattice of covalently bonded carbon atoms.

Diamond is a 3D network lattice of covalently bonded carbon atoms, far right.

Graphite, another allotrope of carbon, is a 2D network lattice of covalently bonded carbon atoms, left.

A 3D network lattice of carbon ions held together by ionic bonds. Does not exist, as carbon does not form ions and elements cannot be ionic, only compounds can.

A 3D network lattice of carbon ions in a sea of mobile valence electrons held together by metallic bonds. This description is more metallic and similar to the description of graphite, which can conduct electricity, but not diamond.

A 3D network lattice of carbon atoms held together by hydrogen bonding and dispersion forces. Hydrogen bonding and dispersion forces are intermolecular forces, although dispersion forces are everywhere, but very weak.

(A) is trigonal bipyramidal; (B) is triangular planar; (C) is linear. (E) is bent.

HBr is a strong acid when dissolved in water. This means that it is also a strong electrolyte.

The Arrhenius equation is ,

where k is the rate constant, E_a is the activation energy, T is the Kelvin temperature, and A is called the preexponential constant. All of these can be determined as long as the correct measurements are made. Therefore (A), (B), and (C) can be evaluated using kinetic methods.

The valence shell is the outer shell of an element. It is the electrons in the valence shell that interact to form compounds, either ionic or covalent. If the valence shell ends in the 4th energy level, this means the compound must be in the fourth row of the periodic table, therefore eliminating answer options A, B, and E. The valence shell shows a total of 7 valence electrons, 2 from the s and 5 from the p. The only element that has 7 valence electrons and is in the 4th row is Bromine (Br).

The responses for (B) and (D) indicate a nonspontaneous process. The response in (C) may indicate a spontaneous process, but it is not sufficient for a spontaneous reaction. Only response (A) is universally true for a spontaneous reaction.

In a mixture of gases, the total gaseous pressure is the sum of the partial pressures of all gases, according to Dalton’s law of partial pressure.