How many protons, neutrons, and electrons are in an  atom?

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.

Which of the following properties generally decreases across the periodic table from sodium to chlorine?

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?

Which of the following lists the substances F2, HCl, and HF in order of increasing boiling point?

The structural formula of the glycinium cation is shown in the figure. Arrows indicate the pKa values for the labile protons in the molecule. Which statement is true about the geometry of 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.

At room temperature I2(s) is a molecular solid. Which of the following provides a characteristic of I2(s) with a correct explanation?

Which of the following represents the ground state electron configuration for the Mn3+ ion? (Atomic number Mn = 25)

Which of the following could be the identity of a white crystalline solid that exhibits the following properties? It melts at 320°C. It does not conduct electricity as a solid. It conducts electricity in an aqueous solution.

Which of the following best represents the ground-state electron configuration for an atom of selenium?