A compound $(\mathrm{X})$ when treated with $\mathrm{CuSO}_4$ solution yields a brown precipitate.On adding hypo solution the precipitate turns white.The compound $(\mathrm{X})$ is
$KBr$
$\mathrm{K}_2 \mathrm{CrO}_3$
$KI$
$\mathrm{K}_3 \mathrm{PO}_4$
Three engines $\mathrm{A}, \mathrm{B}$ and C take steam at $130^{\circ} \mathrm{C}$ and reject it at $20^{\circ} \mathrm{C}, 40^{\circ} \mathrm{C}$ and $50^{\circ} \mathrm{C}$ respectively.The most efficient engine will be
A
B
C
All the three engines will be equally efficient
In a conductance experiment, aqueous $\mathrm{AgNO}_3$ solution is added to aqueous KCl solution gradually and simultaneously the molar conductivity ( $\lambda_{\mathrm{m}}$ ) is measured. The correct plot of $\lambda_{\mathrm{m}}$ versus volume of $\mathrm{AgNO}_3$ solution is




Indicate the major product of the following reaction:





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