Electrovalent bond formation depends on

The number of unit cells in $58.5 \ g$ of $NaCl$ is nearly

The Compton effect demonstrates that:

Which of the following compounds does not give an oxyacid of the central atom upon hydrolysis?

The vector $c \cdot (b+c) \times (a+b+c)$ is equal to

$A$ metal wire $PQ$ slides on parallel metallic rails having a separation of $0.25\ m$,each having negligible resistance. There is a $2\,\Omega$ resistor and a $10\ V$ battery as shown in the figure. $A$ uniform magnetic field of magnitude $0.5\ T$ is directed into the plane of the paper. $A$ force of $0.5\ N$ to the left is required to keep the wire $PQ$ moving with a constant speed to the right. With what speed is the wire $PQ$ moving? (Neglect self-inductance of the loop)