When arranging the copper mines of Rajasthan from north to south, the correct order is:
- Khetri (ii), located in the northern part of Rajasthan, is the first.
- Alwar (iv) comes next, located south of Khetri.
- Bhilwara (i) is further south, located in the southern part of the state.
- Udaipur (iii) is located at the southernmost position among the listed cities.
Thus, the correct order is: Khetri (ii), Alwar (iv), Bhilwara (i), and Udaipur (iii).

Standard electrode potential for \( \text{Sn}^{4+}/\text{Sn}^{2+} \) couple is +0.15 V and that for the \( \text{Cr}^{3+}/\text{Cr} \) couple is -0.74 V. The two couples in their standard states are connected to make a cell. The cell potential will be:
To calculate the cell potential (\( E^\circ_{\text{cell}} \)), we use the standard electrode potentials of the given redox couples.
Given data:
\( E^\circ_{\text{Sn}^{4+}/\text{Sn}^{2+}} = +0.15V \)
\( E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0.74V \)
A carpenter needs to make a wooden cuboidal box, closed from all sides, which has a square base and fixed volume. Since he is short of the paint required to paint the box on completion, he wants the surface area to be minimum.
On the basis of the above information, answer the following questions :
Find a relation between \( x \) and \( y \) such that the surface area \( S \) is minimum.