Zero error belongs to the category of

Two students $P$ and $Q$ perform an experiment to verify Ohm's law for a conductor with resistance $R$. They use a current source and a voltmeter with least counts of $0.1 \, mA$ and $0.1 \, mV$,respectively. The plots of the variation of voltage drop $V$ across $R$ with current $I$ for both are shown below. Which statement is most likely to be correct?

If there is a positive error of $50\%$ in the measurement of velocity of a body,then the error in the measurement of kinetic energy is .............. $\%$

$A$ wire has a mass $0.3 \pm 0.003 \, g$,radius $0.5 \pm 0.005 \, mm$ and length $6 \pm 0.06 \, cm$. The maximum percentage error in the measurement of its density is .......... $\%$

The radius of a sphere is measured to be $(7.50 \pm 0.85) \, cm$. Suppose the percentage error in its volume is $x$. The value of $x$,to the nearest integer is .....$\%$

The length and width of a rectangular room are measured to be $3.95 \pm 0.05 \,m$ and $3.05 \pm 0.05 \,m$,respectively. The area of the floor is .................... $m^2$