To determine which metal's extraction does not commonly involve the use of cyanide salts, we must understand the methods commonly employed in the extraction of the given metals: Zinc, Gold, Silver, and Copper.
Given the above explanations, the use of cyanide is not common in the extraction of copper. Therefore, the correct answer is that copper does not typically involve cyanide salts in its extraction.
A block of mass 1 kg is pushed up a surface inclined to horizontal at an angle of \( 60^\circ \) by a force of 10 N parallel to the inclined surface. When the block is pushed up by 10 m along the inclined surface, the work done against frictional force is:

[Given: \( g = 10 \) m/s\( ^2 \), \( \mu_s = 0.1 \)]
A gas can be taken from A to B via two different processes ACB and ADB. When path ACB is used, \( 60 J \) of heat flows into the system and \( 30 J \) of work is done by the system. If path ADB is used, the work done by the system is \( 10 J \). The heat flow into the system in path ADB is:
