Of the following molecules, which has the largest dipole moment?

The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?

How many moles of Na+ ions are in 100 mL of 0.100 M Na3PO4 (aq)?

The structural formula of the glycinium cation is shown in the figure. Arrows indicate the pKa values for the labile protons in the molecule. What is the approximate H – O – C bond angle in the glycinium cation?   The figure presents a Lewis diagram of a glycinium cation with a positive 1 charge. There is a row of atoms, H, N, C, C, O, and H connected with single bonds. The N atom is connected to two additional H atoms with single bonds. The C atom on the left is connected to two H atoms with single bonds. The C atom on the right is connected to an additional O atom with a double bond. Both O atoms have two nonbonding pairs of electrons. The structure has brackets around it, and there is a plus sign at the top right, indicating that the species has a positive one charge. The leftmost H atom is labeled p K sub a equals 9.6. The rightmost H atom is labeled p K sub a equals 2.3.

Equal masses of He and Ne are placed in a sealed container. What is the partial pressure of He if the total pressure in the container is 6 atm?

To determine the moles of Fe3+(aq) in a 100. mL sample of an unknown solution, excess KSCN(s) is added to convert all the Fe3+(aq) into the dark red species FeSCN2+(aq), as represented by the equation below. The absorbance of FeSCN2+(aq) at different concentrations is shown in the graph below. Fe3+(aq) + KSCN(s) → FeSCN2+(aq) + K+(aq) The figure presents the graph in the first quadrant of a coordinate plane. The horizontal axis is labeled “Concentration of F e S C N with a positive 2 charge, in Molar,” and the following three numbers are indicated: 0, 5 times 10 to the negative 5, and 10 times 10 to the negative 5, in increments of 1 times 10 to the negative 5. The vertical axis is labeled “Absorbance at 453 nanometers,” and the numbers 0 through 0 points 5 0, in increments of 0 point 1 0, are indicated. The line of best fit is drawn. The line begins where the axes meet. It moves steadily upward and to the right passing through the point 5 times 10 to the negative 5 Molar and 0 point 2 5 absorbance. The line ends at 10 times 10 to the negative 5 Molar and 0 point 5 0 absorbance. There are 6 data points along the line. 1 point is at the origin, 3 points are above the line, and 2 points are below. If the absorbance of the mixture is 0.20 at 453 nm, how many moles of Fe3+(aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) is negligible.)

The first five ionization energies of an unknown element are listed in the table. Which of the following statements correctly identifies the element and cites the evidence supporting the identification?  Ionization Energy (kJ/mol)First578Second1,817Third2,745Fourth11,577Fifth14,842

Based on Coulomb’s Law and the information in the table, which of the following cations is most likely to have the weakest interaction with an adjacent water molecule in an aqueous solution? IonIonic Radius (pm)Li+60Na+95Ca2+99In3+81

The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of the periodic properties, which of the following compounds can most likely be used as a fire-resistance chemical?

Which of the following elements has the lowest first-ionization energy?