chem

What is the scientific definition of an element?

A pure substance that cannot be split into anything simpler by chemical changes.

What gas is produced when iron reacts with dilute hydrochloric acid, and how can it be identified?

Hydrogen gas (H2H2​), which burns with a pop sound when tested with a burning splint.

What gas is released when iron(II) sulphide reacts with dilute hydrochloric acid, and what is its distinctive odor?

Hydrogen sulfide gas ($H_2S$), which has a characteristic smell of rotten eggs.

How does the magnetic behavior of an iron and sulphur mixture compare to the compound iron(II) sulphide?

The mixture of iron and sulfur retains the magnetic properties of iron, while iron(II) sulfide is not magnetic due to its ionic bond.

What defines a saturated solution at a specific temperature?

A saturated solution at a specific temperature is defined as a solution in which the maximum amount of solute has been dissolved in the solvent, and any additional solute will remain undissolved.

What products are formed when solid red mercury(II) oxide is thermally decomposed?

The products formed when solid red mercury(II) oxide is thermally decomposed are mercury ($Hg$) and oxygen gas ($O_2$).

How can a colourless liquid formed from burning hydrogen be confirmed as pure water? Definition: By boiling the liquid to observe whether it boils at a fixed temperature of 100∘C100∘C.

If the liquid remains in the same state and boils consistently at $100^\text{°C}$ at standard atmospheric pressure, it is confirmed to be pure water.

What are the most abundant element and the most abundant compound found in dry air?

The most abundant element found in dry air is nitrogen ($N$), while the most abundant compound is oxygen ($O_2$).