
- Transistors (A) use a battery with an anode of Zn/Hg and a cathode of HgO + C.
- Hearing aids (B) use a battery with an anode of Zn and a cathode of Carbon.
- Inverters (C) use a hydrogen fuel cell as the energy source.
- Apollo space ship (D) uses a battery with an anode of Pb and a cathode of PbO\(_2\).
Therefore, the correct matching is \( \boxed{(A)-(III), (B)-(I), (C)-(IV), (D)-(II)} \).


MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.
MX(s) $\rightleftharpoons M^{+(aq) }+ X^{-}(aq)$; $K_{sp} = 10^{-10}$
If the standard reduction potential for $M^{+}(aq) + e^{-} \rightarrow M(s)$ is $(E^{\circ}_{M^{+}/M}) = 0.79$ V, then the value of the standard reduction potential for the metal/metal insoluble salt electrode $E^{\circ}_{X^{-}/MX(s)/M}$ is ____________ mV. (nearest integer)
[Given : $\frac{2.303 RT}{F} = 0.059$ V]
The figure shows a pipe with cross-section area 10 \( cm^2 \). Water flows from one end with velocity 20 cm/s. The other end of the pipe is closed and consists of 10 holes each of area 30 \( mm^2 \). Find the velocity of water coming out from each hole: 
Which of the following best represents the temperature versus heat supplied graph for water, in the range of \(-20^\circ\text{C}\) to \(120^\circ\text{C}\)? 