The major product of the following reaction is:

$A$ piece of copper and another of germanium are cooled from room temperature to $80\, K$. The resistance of :

Suppose a pure $Si$ crystal has $5 \times 10^{28} \text{ atoms } m^{-3}$. It is doped by $1 \text{ ppm}$ concentration of pentavalent $As$. Calculate the number of electrons and holes. Given that $n_{i} = 1.5 \times 10^{16} \text{ m}^{-3}$.

In an $AC$ circuit,the current is given by $i = 5 \sin(100t - \frac{\pi}{2}) \text{ A}$ and the $AC$ potential is $V = 200 \sin(100t) \text{ V}$. Then the power consumption is $....$ watt.

Sulphide ores of metals are usually concentrated by froth floatation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?

The component of vector $\vec{A} = 2\hat{i} + 3\hat{j}$ along the vector $\vec{B} = \hat{i} + \hat{j}$ is: