Write equations for the reactions of
$(i)$ iron with steam
$(ii)$ calcium and potassium with water
$(i)$ $\underset{Iron}{\mathop{3F{{e}_{(s)}}}}\,\,+\,\underset{Steam}{\mathop{4{{H}_{2}}{{O}_{(g)}}}}\,\,\to \,\underset{Iron\,(II,III)\,oxide}{\mathop{F{{e}_{3}}{{O}_{4(aq)}}}}\,\,+\underset{Hydrogen}{\mathop{\,4{{H}_{2(g)}}}}\,$
$(ii)$ $C{{a}_{(s)}}+2{{H}_{2}}{{O}_{(l)}}\to Ca{{(OH)}_{2(aq)}}$ $+{{H}_{2(g)}}+\text{ Heat }$
$(iii)$$\underset{\begin{smallmatrix}
\text{Calcium}\,\text{/} \\
\text{Potassium}
\end{smallmatrix}}{\mathop{2{{K}_{(s)}}}}\,+\underset{water}{\mathop{2{{H}_{2}}{{O}_{(l)}}}}\,\to \underset{\begin{smallmatrix}
\text{Calcium Hydroxide /} \\
\text{Potassium hydroxide}
\end{smallmatrix}}{\mathop{2KO{{H}_{(aq)}}}}\,+\underset{Hydrogen}{\mathop{{{H}_{2(g)}}}}\,+\text{ Heat }$
Give reasons : Platinum, gold and silver are used to make jewellery.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
$(i)$ Write the electron-dot structures for sodium. oxygen and magnesium.
$(ii)$ Show the formation of $Na _{2} O$ and $MgO$ by the transfer of electrons.
$(iii)$ What are the ions present in these compounds ?
Give reasons : Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Which of the following methods is suitable for preventing an iron frying pan from rusting ?