Write down the formula of Aluminium oxide.

A. $\mathrm{AlO}$

B. ${\mathrm{Al}}_2{O}_3$

C. ${\mathrm{Al}}_3{O}_2$

"Enter your correct answer as A, B or C."

Write down the formula of Calcium hydroxide.

A. $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$

B. $\mathrm{CaOH}$

C. $\mathrm{Ca}{\left(\mathrm{OH}\right)}_3$

"Enter your correct answer as A, B or C."

Write down the formula of Potassium sulphide.

A. ${\mathrm{KS}}_2$

B. ${\mathrm{K}}_2{\mathrm{S}}_3$

C. ${\mathrm{K}}_2\mathrm{S}$

"Enter your correct answer as A, B or C."

Write down the formula of Phosphorus pentachloride.

A. ${\mathrm{PCl}}_5$

B. $5\mathrm{PCl}$

C. ${\mathrm{P}}_5\mathrm{Cl}$

"Enter your correct answer as A, B or C."

Write down the formula of Boron trifluoride.

A. ${\mathrm{B}}_3\mathrm{F}$

B. ${\mathrm{BF}}_3$

C. $3\mathrm{BF}$

"Enter your correct answer as A, B or C."

Write down the formula of Copper(II) sulphate pentahydrate.

A. ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$

B. ${\mathrm{CuSO}}_4.{\left({\mathrm{H}}_2\mathrm{O}\right)}_5$

C. $5{\mathrm{CuSO}}_4.{\mathrm{H}}_2\mathrm{O}$

"Enter your correct answer as A, B or C."

Write down the name of the compound represented by the formula: ${\mathrm{NaNO}}_3$

(Sodium nitrite/ Sodium nitrate)