Which of the following pairs is incorrect?

$A$ train leaves Pune at $7:30\,am$ and reaches Mumbai at $11:30\,am$. Another train leaves Mumbai at $9:30\,am$ and reaches Pune at $1:00\,pm$. Assuming that the two trains travel at constant speeds,at what time do the two trains cross each other?

$A$ body cools from $62^{\circ}C$ to $50^{\circ}C$ in $10$ minutes and to $42^{\circ}C$ in the next $10$ minutes. The temperature of the surrounding is ........... $^{\circ}C$.

The solution of $x \frac{dy}{dx} = y + x e^{y/x}$ with $y(1) = 0$ is

$A$ household refrigerator with a coefficient of performance $1.2$ removes heat from the refrigerated space at the rate of $60 \ kJ/min$. What would be the cost of running this fridge for one month ($30$ days)? (Assume it is used for $4$ hours each day and the cost of one electrical unit is $6 \ Rs$.)

$A$ pair of lines $S=0$ together with the lines given by the equation $8 x^2-14 x y+3 y^2+10 x+10 y-25=0$ form a parallelogram. If its diagonals intersect at the point $(3,2)$,then the equation $S=0$ is