Iron filings and sulphur were mixed together and divided into two parts,$A$ and $B$. Part $A$ was heated strongly while Part $B$ was not heated. Dilute hydrochloric acid was added to both the parts and evolution of gas was seen in both the cases. How will you identify the gases evolved?

Rusting of an article made of iron is called:

State the separation technique you would apply for the separation of the following:
$(a)$ Sodium chloride from its solution in water
$(b)$ Tea leaves from tea
$(c)$ Iron pins from sand
$(d)$ Different pigments from an extract of leaves
$(e)$ Butter from curd
$(f)$ Fine mud particles suspended in water.

Fill in the blanks:
$(a)$ $A$ colloid is a .......... mixture and its components can be separated by the technique known as .........
$(b)$ Ice,water,and water vapour look different and display different ......... properties but they are ......... the same.
$(c)$ $A$ mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of ......... and the lower layer will be that of .........
$(d)$ $A$ mixture of two or more miscible liquids,for which the difference in the boiling points is less than $25 \, K$,can be separated by the process called .........
$(e)$ When light is passed through water containing a few drops of milk,it shows a bluish tinge. This is due to the ......... of light by milk and the phenomenon is called ......... . This indicates that milk is a ......... solution.

What would you observe when:
$(a)$ a saturated solution of potassium chloride prepared at $60^{\circ} C$ is allowed to cool at room temperature?
$(b)$ an aqueous sugar solution is heated to dryness?
$(c)$ a mixture of iron filings and sulphur powder is heated strongly?

$A$ mixture of sulphur and carbon disulphide is