Round 2

The figure above shows a thin, square, nonconducting sheet of positive charge uniformly distributed over its area. The length of each side of the sheet is a. Point C is at the center of the sheet. Point X is a distance d above the center of the sheet, and point Y is a distance 2d above the center of the sheet. Assume a >> d. The effect of gravity is negligible.

• E/4

• E/2

• E

• 2E

Conductor Y is then moved closer to conductor X until it is just outside a closed cubical surface containing conductor X, as shown in the figure above. How would the total electric flux through the cubical surface change as conductor Y is moving?

• It would increase

• It would decrease

• It would change sign

• It would remain constant, with the flux through each side of the surface also remaining constant.

• It would remain constant, but the flux through each side of the cubical surface would change.

Which of the following will increase the magnetic field on the axis of a long solenoid?

I. Increasing the current in the solenoid

II. Increasing the cross-sectional area of the solenoid

III. Inserting an iron core into the solenoid

• I only

• III only

• I and III only

• II and III only

• I, II, and III

Three identical spheres are equally spaced from one another. Spheres 1 and 2 have charge +Q, and sphere 3 has a charge of –Q, as shown in the figure above. Five different positions are labeled A, B, C, D, and E. Positions A, B, and C are all the same distance from sphere 3. Positions C, D, and E are all the same distance from sphere 2. All spheres and points lie in the same plane.

• A

• B

• C

• D

• E

Two stationary point charges of unknown magnitude and sign are isolated from all other charges. If the electric field strength is zero at the midpoint of the line joining them, which of the following can be concluded about the charges?

• They are equal in magnitude but opposite in sign.

• They are equal in magnitude and have the same sign.

• They are not necessarily equal in magnitude but have opposite signs.

• They are not necessarily equal in magnitude but have the same sign.

A student performs an acid-base titration and plots the experimental results in the graph above. Which of the following statements best explains the experimental findings?

• A strong acid was titrated with a strong base, as evidenced by the equivalence point at pH = 7

• A strong acid was titrated with a strong base, as evidenced by the equivalence point at pH > 7

• A weak acid was titrated with a strong base, as evidenced by the equivalence point at pH > 7

• A weak acid was titrated with a weak base, as evidenced by the equivalence point at pH approximately 7

Based on the K_sp values in the table above, a

saturated solution of which of the following

compounds has the highest [Cl^-] ?

• PbCl₂

• CuCl

• AgCl

• Hg₂Cl₂

Which of the following will most likely increase the rate of the reaction represented above?

• Decreasing the temperature of the reaction system

• Adding a heterogeneous catalyst to the reaction system

• Increasing the volume of the reaction vessel using a piston

• Removing some H₂(g) from the reaction system

A mixture containing equal numbers of moles of ethyl acetate and butyl acetate was separated using distillation. Based on the diagrams shown above, which of the following identifies the substance that would be initially present in higher concentration in the distillate and correctly explains why that occurs?

• Ethyl acetate, because it has fewer CC bonds to break

• Ethyl acetate, because it has a shorter carbon chain and weaker London dispersion forces

• Butyl acetate, because it has more CC bonds to break

• Butyl acetate, because it has a longer carbon chain and weaker dipole-dipole attractions

Based on the ionization energies of element X given in the table above, which of the following is most likely the empirical formula of an oxide of element X?

• XO₂

• X₂O

• X₂O₃

• X₂O₅