If $4\,P(A) = 6\,P(B) = 10\,P(A \cap B) = 1,$ then $P\left( \frac{B}{A} \right) = $

$A$ black metal foil is warmed by radiation from a small sphere at temperature $T$ and at a distance $d$. It is found that the power received by the foil is $P$. If both the temperature and the distance are doubled,the power received by the foil will be

If $x-y+1=0$ meets the circle $x^2+y^2+y-1=0$ at $A$ and $B$,then the equation of the circle with $AB$ as diameter is

Which of the following are photosynthetic bacteria?

The ratio of angular speeds of the minute hand and the hour hand of a watch is

Which one of the following is a matching set of phylum and its three examples?