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A 1.0 mol sample of He(g) at 25°C is mixed with a 1.0 mol sample of Xe(g) at 50°C. Which of the following correctly predicts the changes in average kinetic energy and the average speed of the Xe(g) atoms that will occur as the mixture approaches thermal equilibrium?

The following table shows the first ionization energy and the atomic radius of several elements. Which of the following best helps to explain the deviation of the first ionization energy of oxygen from the overall trend?   Element First Ionization Energy (kJ/mol) Atomic Radius (pm) B 801 85 C 1086 77 N 1400 75 O 1314 73 F 1680 72 Ne 2080 70

1s2 2s2 2p6 3s2 3p3   Atoms of an element, X, have the electronic configuration shown above. The compound most likely formed with magnesium, Mg, is

Which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference?

Which of the statements, if true, would support the claim that the NO3– ion, represented in the figure, has three resonance structures?   The figure presents a Lewis diagram. There is a Nitrogen atom bonded to three Oxygen atoms, two of them with single bonds and one with a double bond. The oxygen atoms connected with single bonds each have three nonbonding pairs of electrons. The oxygen atom connected with a double bond has two nonbonding pairs of electrons. The diagram is contained in brackets, with a negative sign to its upper right.

Select the answer that best fits the statement: Is isomeric with CH3CH2CHO.

Lewis electron-dot diagrams for CO2 and SO2 are given. The molecular geometry and polarity of the two substances are Lewis structures for C O 2 and S O 2. C O 2 is composed of oxygen atoms on either side of a carbon atom, connected by double bonds. The oxygen atoms have two lone electron pairs. S O 2 is composed of oxygen atoms on either side of a sulfur atom. The oxygen atom on the left has three lone electron pairs and is connected to sulfur by a single bond. The oxygen atom on the right has two lone electron pairs and is connected to sulfur by a double bond. There is one lone pair of electrons on the sulfur atom.

A sample of a compound contains 3.21g of sulfur and 11.4g of fluorine. Which of the following represents the empirical formula of the compound?

At 27°C, five identical rigid 2.0 L vessels are filled with N2(g) and sealed. Four of the five vessels also contain a 0.050 mol sample of NaHCO3(s), NaBr(s), Cu(s), or I2(s), as shown in the diagram. A diagram shows five boxes, numbered 1 through 5. Box 1 contains 0.050 mol of N a H C O 3 (solid). Box 2 contains 0.050 mol N a B r (solid). Box 3 is empty. Box 4 contains 0.050 mol C u (solid). Box 5 contains 0.050 mol I 2 (solid). The volume taken up by the solids is negligible, but the initial pressure of N2(g) in each vessel is 720 mm Hg. All four vessels are heated to 127°C and allowed to reach a constant pressure. The gas particles in Vessel 3 at 27°C are represented in the diagram below. A diagram shows four gas molecules in a box, moving in random directions. Two of the four molecules have long arrows, the third one has a shorter arrow, and the fourth one has the shortest arrow. The lengths of the arrows represent the speeds of the particles. Which of the following diagrams best represents the particles when Vessel 3 is heated to 127°C?

What is the empirical formula of an oxide of chromium that is 48 percent oxygen by mass?