Question: Read this and answer the question

Hayek had a long-standing and close friendship with philosopher of science Karl Popper, also from Vienna. In a letter to Hayek in 1944, Popper stated, "I think I have learnt more from you than from any other living thinker, except perhaps Alfred Tarski." (See Hacohen, 2000). Popper dedicated his Conjectures and Refutations to Hayek. For his part, Hayek dedicated a collection of papers, Studies in Philosophy, Politics, and Economics, to Popper and, in 1982, said that "ever since his Logik der Forschung first came out in 1934, I have been a complete adherent to his general theory of methodology". Popper also participated in the inaugural meeting of the Mont Pelerin Society. Their friendship and mutual admiration, however, do not change the fact that there are important differences between their ideas.

Who is the only exception from whom Hayek claims to have learned more than he did from Popper?
Answer: Alfred Tarski
Question: Read this and answer the question

The X-ray crystal density method is primarily a method for determining the Avogadro constant NA but as the Avogadro constant is related to the Planck constant it also determines a value for h. The principle behind the method is to determine NA as the ratio between the volume of the unit cell of a crystal, measured by X-ray crystallography, and the molar volume of the substance. Crystals of silicon are used, as they are available in high quality and purity by the technology developed for the semiconductor industry. The unit cell volume is calculated from the spacing between two crystal planes referred to as d220. The molar volume Vm(Si) requires a knowledge of the density of the crystal and the atomic weight of the silicon used. The Planck constant is given by

What is the primary method for determining the Avogadro constant?
Answer: The X-ray crystal density method
Question: Read this and answer the question

CD-R recordings are designed to be permanent. Over time, the dye's physical characteristics may change causing read errors and data loss until the reading device cannot recover with error correction methods. The design life is from 20 to 100 years, depending on the quality of the discs, the quality of the writing drive, and storage conditions. However, testing has demonstrated such degradation of some discs in as little as 18 months under normal storage conditions. This failure is known as disc rot, for which there are several, mostly environmental, reasons.

What can cause sudden disc degradation?
Answer:
disc rot