$A$ weight $W$ can be hung in any of the following four ways by using the same string. In which case is the string more likely to break?

$A$ straight line $L$ at a distance of $4$ units from the origin makes positive intercepts on the coordinate axes,and the perpendicular drawn from the origin to this line makes an angle of $60^{\circ}$ with the line $x+y=0$. Then the equation of the line $L$ is

Two oxides of nitrogen,$NO$ and $NO_2$,react together at $253 \ K$ to form a compound of nitrogen $X$. $X$ reacts with water to yield another compound of nitrogen $Y$. The shape of the anion of $Y$ molecule is:

Ferric sulphate on heating gives:

$3$ moles of ethanol react with $1$ mole of phosphorus tribromide to form $3$ moles of bromoethane and $1$ mole of $X$. Which of the following is $X$?

Two blocks are connected by a spring. The combination is suspended,at rest,from a string attached to the ceiling,as shown in the figure. The string breaks suddenly. Immediately after the string breaks,what is the initial downward acceleration of the upper block of mass $2\,m$?