Consider a sample of helium gas in a container fitted with a piston as pictured below. the piston is frictionless, but has a mass of 10.0 kg. how many of the following processes will cause the piston to move away from the base and decrease the pressure of the gas? assume ideal behavior.
i. heating the helium.
ii. removing some of the helium from the container.
iii. turning the container on its side.
iv. decreasing the pressure outside the container.
a) 0
b) 1
c) 2
d) 3
e) 4

One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(ii) carbonate, in concentrated sulfuric acid. the sulfuric acid reacts with the copper(ii) carbonate to produce a blue solution of copper(ii) sulfate. scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: (s) (aq) (s) (aq) suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. he adds powdered iron to a copper(ii) sulfate sample from the plant until no more copper will precipitate. he then washes, dries, and weighs the precipitate, and finds that it has a mass of .