Four substances have the following electrical properties.

Substance	Electrical property
W	Does not conduct electricity under any condition
X	Conducts electricity only in aqueous solution
y	Conducts electricity in both the molten and solid states
Z	Conducts electricity in both the molten state and in aqueous solution

What are these four substances?

	W	X	y	Z
(A)	$\mathrm{HCl}$	$\mathrm{S}$	$\mathrm{NaCl}$	$\mathrm{Pb}$
(B)	$\mathrm{Pb}$	$\mathrm{HCl}$	$\mathrm{NaCl}$	$\mathrm{S}$
(C)	$\mathrm{S}$	$\mathrm{HCl}$	$\mathrm{Pb}$	$\mathrm{NaCl}$
(D)	$\mathrm{S}$	$\mathrm{NaCl}$	$\mathrm{HCl}$	$\mathrm{Pb}$

Fill in the blanks by selecting the option with the correct words.

The process of removing impurities from impure metal to obtain pure metal is known as _____ of metal. The most widely used method for refining is _____. In this method, the impure metal is taken as _____ and the pure metal is taken at _____.

Shweta was given four squares $P,Q,R$ and $S$ with atomic numbers written on them. She gave the following four statements.

(i) Element $Q$ is a non-metal.

(ii) Square $R$ represents a metal with valency $3$.

(iii) Element $S$ is a metalloid.

(iv) Element $P$ is a metal.

The true statements given by her are ___.

Match column I (method of concentration) with column II (principle involved) and select the appropriate option from the given codes.

Which of the following statements are incorrect?

I. Reactivity of $\mathrm{Al}$ decreases if it is dipped in nitric acid.

II. Carbon can reduce the oxides of $\mathrm{Na}$ and $\mathrm{Mg}$.

III. $\mathrm{NaCl}$ is a good conductor of electricity in solid state.

Read the given statements and mark the correct option.

Statement 1: Articles made of aluminium do not corrode even though it is an active metal.

A brief information about a few elements is given below:

$P$: It is used in making electrodes.

$Q$: It is required for combustion.

$R$: It is used to preserve food.

$S$: It is used as fungicide.

$P,Q,R$ and $S$ are respectively.