Which of the following is absent in prokaryotes?

$A$ long straight wire along the $z$-axis carries a current $I$ in the negative $z$-direction. The magnetic vector field $\vec B$ at a point having coordinates $(x, y)$ in the $z = 0$ plane is

If $2.2 \, kW$ power is transmitted through a $10 \, \Omega$ line at $22000 \, V$,the power loss in the form of heat will be ............. $W$.

In which of the following,ortho/para substitution by an electrophile is very facile?

An electric motor operating on a $60\,V$ $dc$ supply draws a current of $10\,A$. If the efficiency of the motor is $50\%$,the resistance of its winding is....$\Omega$

For the reaction sequence given below, the correct statement$(s)$ is$($are$)$
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$($In the options, $X$ is any atom other than carbon and hydrogen, and it is different in $P , Q$ and $R )$