CAIE IGCSE Chemistry 1.1 Solids Liquids and Gases Topic Practice

A compound, X , has a melting point of $71^{\circ} \mathrm{C}$ and a boiling point of $375^{\circ} \mathrm{C}$.
Which statement about X is correct?

In which state does $1 \mathrm{dm}^{3}$ of methane contain the most particles?

This question is about the elements sodium and fluorine and the compound sodium fluoride.

Some properties of sodium, fluorine and sodium fluoride are shown in Table 3.1.

Deduce the physical state of fluorine at $-200^{\circ} \mathrm{C}$. Use the data in Table 3.1 to explain your answer.
physical state
explanation

Hydrogen iodide, HI, decomposes into iodine and hydrogen. The reaction is reversible.

A gas syringe containing a mixture of hydrogen iodide, iodine and hydrogen gases was sealed. After reaching equilibrium the mixture was a pale purple colour.

The plunger of the gas syringe is pushed in. The position of equilibrium does not change. The colour of the gaseous mixture turns darker purple.

The temperature remains constant.

Suggest why the colour of the gaseous mixture turns darker purple even though the position of equilibrium does not change.

A mixture of ice and water is left to stand and the ice melts.

Which row describes what happens as the ice is melting?

A gas is heated. The pressure is kept constant.
Which statement describes the behaviour of the particles in the gas?