Answer exactly one question from this section.

Do not answer more than the required number of questions in this section. Extra answers will not be marked.

1.

The dew point is the temperature at which condensation of water vapor in the atmosphere becomes spontaneous. Suppose that the partial pressure of water vapor is $1.0\times 10^{-2}\,\mathrm{bar}$. What is the dew point, in degrees Celsius? [10 marks]

2.

Discuss the organization of elements in the periodic table in relation to quantum mechanics. [10 marks]

3.

(a)

X rays with a wavelength of 154pm refract from a crystal at an angle of $10.4^\circ$. If this is a first-order reflection, what is the corresponding interplane spacing in the crystal? [2 marks]

(b)

Predict all other reflections corresponding to this interplane spacing. [8 marks]