What is the percentage concentration of sodium hydroxide solution used in the Bayer process (in $\%$)?

$(i)$ Explain the steps for extraction of copper from its sulphide ore. Write the balanced equations involved in the process.
$(ii)$ What is meant by refining of metals? Draw a diagram of electrolytic refining of copper and name the substances used as cathode, anode, and the electrolyte.

Make the correct pairs from below mentioned $X$ and $Y$:

$X$	$Y$
$1$. Extraction of sulphur	$p$. Contact process
$2$. Production of nitric acid	$q$. Frasch method
$3$. Production of sulphuric acid	$r$. Haber's process
$4$. Production of ammonia gas	$s$. Ostwald's method

$A$ metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.

Which ore is concentrated by the froth flotation process?

$(i)$ Define the term 'anode mud'. Name the electrode made of pure metal.
$(ii)$ Give the reactions taking place at cathode and at anode during the electrolytic refining of copper.