When iron sulfide is heated in air,a sulfur oxide $A$ is formed. When $A$ is dissolved in water,it produces an acid. What is the basicity of this acid?

$A$ wire of length $l$ is bent into a circular loop of radius $R$ and carries a current $I$. The magnetic field at the centre of the loop is $B$. The same wire is now bent into a double loop of equal radii. If both loops carry the same current $I$ and it is in the same direction,the magnetic field at the centre of the double loop will be

If the variable line $y = kx + 2h$ is tangent to an ellipse $2x^2 + 3y^2 = 6$,then the locus of $P(h, k)$ is a conic $C$ whose eccentricity equals

Persistent nucellus in the seed is known as

The binding energy per nucleon versus mass number curve for nuclei is shown in the figure. $W, X, Y$ and $Z$ are four nuclei indicated on the curve. The process that would release energy is

$A$ drop of liquid of diameter $2.8\, mm$ breaks up into $125$ identical drops. The change in energy is nearly ......... $ergs$ (Surface tension $= 75\, dyne/cm$)