Which of the following is a ferrous alloy?

Which of the following is not correctly matched?

Identify the correct statements from the following:
$I$. Brass is an alloy of copper and nickel
$II$. Bronze is an alloy of copper and zinc
$III$. German silver is an alloy of copper,zinc and nickel
$IV$. Brass is an alloy of copper and zinc

To obtain steel entirely free from sulphur and phosphorus,the process used is

The percentage of silver in 'German silver' is:

Given below are two statements related to Ellingham diagram:
Statement-$I$ : Ellingham diagrams can be constructed for formation of oxides,sulfides and halides of metals.
Statement-$II$ : It consists of plots of $\Delta_f H^0$ vs $T$ for formation of oxides of elements.
In the light of the above statements,choose the most appropriate answer from the options given below: