In an investigation of the electronic absorption spectrum of a particular element, it is found that a photon having l = 500 nm provides just enough energy to promote an electron from the second quantum level to the third. From this information, we can deduce

The heat combustion of acetylene, C2H2(g), at 25°C is –1299 kJ/mol. At this temperature, ∆Hf° values for CO2(g) and H2O(l) are –393 and –286 kJ/mol, respectively. Calculate ∆Hf° for acetylene.

Consider the following orderings. I. Na+ < Mg2+ < Al3+ < Si4+ II. Be < Mg < Ca < Sr III. I < Br < Cl < F IV. Al < Si < P < Cl Which of these give(s) a correct trend in ionization energy?

How much heat is required to raise the temperature of a 5.75-g sample of iron (specific heat = 0.450 J/g°C) from 25.0°C to 79.8°C?

How many f orbitals have n = 6?

Choose the correct equation for the standard enthalpy of formation of CO(g), where ∆Hf° for CO = –110.5 kJ/mol (gr indicates graphite).

Consider the reaction:          When a 21.1-g sample of ethyl alcohol (molar mass = 46.07 g/mol) is burned, how much energy is released as heat?

What is the wavelength of a photon of red light (in nm) whose frequency is 4.55 x 1014 Hz?

A 79-year-old patient with mild cognitive impairment is starting physical therapy. The patient often struggles to remember multi-step instructions and needs frequent reminders.  Which communication approach would be most effective in helping this patient adhere to the treatment plan? 

The optimal budget for a campaign can be determined using the formula: