The rusting of iron can be prevented by coating it with a layer of:

A. Zinc  
B. Sodium 
C. Chromium 
D. Carbon

When magnesium is burnt in air, a powdery ash $\mathrm{X}$ is formed. $\mathrm{X}$ on dissolving in water forms $\mathrm{Y}$. 

What are (i) $\mathrm{X}$, and (ii) $\mathrm{Y}$? 

When magnesium is burnt in air, a powdery ash $\mathrm{X}$ is formed. $\mathrm{X}$ on dissolving in water forms $\mathrm{Y}$. 

What is the action of $\mathrm{Y}$ on litmus paper? 

When magnesium is burnt in air, a powdery ash $\mathrm{X}$ is formed. $\mathrm{X}$ on dissolving in water forms $\mathrm{Y}$. 

What conclusion do you get about the nature of $\mathrm{Y}$ from its action on litmus paper?

When magnesium is burnt in the air, powdery ash $\mathrm{X}$ is formed. $\mathrm{X}$ on dissolving in water forms $\mathrm{Y}$.

What is the common name of the indigestion-relieving medicine which contains $\mathrm{Y}$? Select from the options:

(Milk of magnesia/ magnesium chloride)

When a grey coloured object made of metal $\mathrm{A}$ is left exposed to damp air for a considerable time, it gets covered with a red-brown flaky coating by the process called $\mathrm{B}$ which eats up the whole object gradually. It is said that the presence of $\mathrm{C}$ and $\mathrm{D}$ is necessary for this process to take place. If this object is galvanised by metal $\mathrm{E}$, then the process $\mathrm{B}$ does not occur.

 Name the metal $\mathrm{A}$ of which the object is made.