The yellow colour solution of $Na_2CrO_4$ changes to orange-red on passing $CO_2$ gas due to the formation of

Blister copper is

$A$ body is thrown vertically upwards and reaches its maximum height in $t$ seconds. The total time from the time of projection to reach a point at half of its maximum height while returning (in seconds) is:

If an electron and a proton have the same de-Broglie wavelength,then the kinetic energy of the electron is

Consider a gas phase reaction which occurs in a closed vessel: $2A \rightarrow 4B + C$. The concentration of $B$ is found to be increased by $5 \times 10^{-3} \ mol \ L^{-1}$ in $10 \ s$. The rate of disappearance of $A$ (in $mol \ L^{-1} \ s^{-1}$) is:

$BF_3$ is used as a catalyst in many industrial processes because of its .....