Identify the reaction for which $\Delta H \neq \Delta E$ :

Which of the following are not electromagnetic waves?

Ethanol when reacted with $PCl_5$ gives $A$,$POCl_3$ and $HCl$. $A$ reacts with silver nitrite to form $B$ (major product) and $AgCl$. $A$ and $B$ respectively are

The length of the latus rectum of the parabola $y^2+8x-2y+17=0$ is

Box $A$ contains $2$ black and $3$ red balls, while Box $B$ contains $3$ black and $4$ red balls. Out of these two boxes, one is selected at random; and the probability of choosing Box $A$ is double that of Box $B$. If a red ball is drawn from the selected box, then the probability that it has come from Box $B$ is:

Two bodies of masses $m_1$ and $m_2$ are initially at rest at an infinite distance apart. They are then allowed to move towards each other under mutual gravitational attraction. Their relative velocity of approach at a separation distance $r$ between them is