Exercise

Which of the following reactions represents a double displacement reaction? 

Potassium and calcium are very reactive metals at the top of the series. Because their ions have different charges, ${\mathrm{K}}^{+}$ and ${\mathrm{Ca}}^{2+}$, their compounds behave differently when heated. Their hydroxides are heated. If the compound decomposes, complete the word equation. If it does not decompose, write 'no reaction'.

$\mathrm{potassium} \mathrm{hydroxide} \to$ _____.

$\mathrm{calcium} \mathrm{hydroxide} \to$ _____.

Write the formulae and then balance the following chemical equations.
Ferric chloride+Ammonium hydroxide$\to$Ferric hydroxide+Ammonium chloride

Adding which of the following to a colourless solution would give an indication that the solution could possibly be hydrochloric acid?

An acid used by goldsmith for dissolving gold is

What is not true about calcination?

Read the following statements:
$\left(\mathrm{P}\right)$ Stainless steel does not rust.
$\left(\mathrm{Q}\right)$ Iron, nickel and chromium form an alloy.
Does statement $\left(\mathrm{Q}\right)$ present a valid explanation for statement $\left(\mathrm{P}\right)$? Justify your answer.

Listed here is the reactivity of certain metals:

From the list above, identify the metal(s) that are likely to be found in a pure state in the Earth's Crust.