What is known as 'Butter of Tin'?

If the lines $2x - 3y = 5$ and $3x - 4y = 7$ are two diameters of a circle of radius $7$,then the equation of the circle is

Two solenoids have identical geometrical construction and the same number of turns,but one is made of thick wire and the other of thin wire. Which of the following quantities are different for the two solenoids?
$(a)$ Self-inductance
$(b)$ Rate of Joule heating if the same current flows through them
$(c)$ Magnetic potential energy if the same current flows through them
$(d)$ Time constant

We can define a facultative parasite as one which:

$A$ plane passing through $(-1, 2, 3)$ and whose normal makes equal angles with the coordinate axes is

The transfer of energy from organism to organism in a natural community establishes