When a hydrogen electron makes a transition from n = 3 to n = 1, which of the following statements is true? I. Energy is emitted. II. Energy is absorbed. III. The electron loses energy. IV. The electron gains energy. V. The electron cannot make this transition.

Which of the following does not have a standard enthalpy of formation equal to zero at 25°C and 1.0 atm?

Given:               Cu2O(s) + O2(g) –> 2CuO(s) ∆H° = –144 kJ Cu2O(s) –> Cu(s) + CuO(s) ∆H° = +11 kJ Calculate the standard enthalpy of formation of CuO(s).

Consider the following specific heats of metals. Metal Specific Heat Zinc 0.387 J/(g°C) Magnesium 1.02 J/(g°C) Iron 0.450 J/(g°C) Silver 0.237 J/(g°C) Lead 0.127 J/(g°C) If the same amount of heat is added to 25.0 g of each of the metals, which are all at the same initial temperature, which metal will have the highest temperature?

An element with the electron configuration [Xe] 6s24f145d7 would belong to which class on the periodic table?

For the reaction:               AgI(s) + Br2(g) –> AgBr(s) + I2(s), ∆H° = –54.0 kJ               ∆Hf° for AgBr(s) = –100.4 kJ/mol               ∆Hf° for Br2(g) = +30.9 kJ/molThe value of ∆Hf° for AgI(s) is:

The first ionization energy of Mg is 735 kJ/mol. The second ionization energy is

The number of unpaired electrons in the outer subshell of a Cl atom is

Of the following elements, which has occupied d orbitals in its ground-state neutral atoms?

CH4(g) + 4Cl2(g) –> CCl4(g) + 4HCl(g), ∆H = –434 kJBased on the above reaction, what energy change occurs when 1.2 moles of methane (CH4) reacts?