Question

The bulb in the given set-up glows only when X is added to it.

Identify X from the following:
*More than one option may be correct.

• A. KOH(aq)
• B. $C_6{H}_{12}{O}_6\left(s\right)$
• C. $C_2{H}_5\mathrm{OH}\left(l\right)$
• D. ${\mathrm{CaCl}}_2\left(\mathrm{aq}\right)$

Answer 1

Answer: (A), (D)

${\mathrm{CaCl}}_2\left(\mathrm{aq}\right)$

The bulb will glow only when there are mobile ions and the circuit is complete.
Ionic compounds like KOH and ${\mathrm{CaCl}}_2\left(\mathrm{aq}\right)$ dissociate in water to furnish ions. Thus, the bulb glows in the presence of KOH(aq) or ${\mathrm{CaCl}}_2\left(\mathrm{aq}\right)$

$\mathrm{KOH}\left(\mathrm{aq}\right)\to K^{+}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$
${\mathrm{CaCl}}_2\left(\mathrm{aq}\right)\to {\mathrm{Ca}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$

$C_6{H}_{12}{O}_6\left(s\right)$ and $C_2{H}_5\mathrm{OH}\left(l\right)$ do not furnish any ions. Thus, the bulb does not glow.