Explain the following term with example:

Endothermic reaction

Explain the following term with example:

Combination reaction

Explain the following term with example:

Balanced equation

Explain the following terms with examples.

Displacement reaction

Give scientific reason:

When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky.

Give scientific reason:

It takes time for pieces of Shahabad tile to disappear in $\mathrm{HCl}$, but its powder disappears rapidly.

Give scientific reason:

While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.

Give scientific reason:

It is recommended to use air tight container for storing oil for long time.

Observe the following picture and write-down the chemical reaction with explanation.