If the gravitational acceleration at the surface of the Earth is $g$,then the increase in potential energy in lifting an object of mass $m$ to a height equal to half of the radius of the Earth from the surface will be

If the lines $x^2+2xy-35y^2-4x+44y-12=0$ and $5x+\lambda y-8=0$ are concurrent,then the value of $\lambda$ is

The locus of the poles of focal chords of the parabola $y^2 = 4ax$ is

Boron in green plants assists in

$A$ wire of length $L$ and $3$ identical cells of negligible internal resistances are connected in series. Due to the current,the temperature of the wire is raised by $\Delta T$ in time $t$. $N$ number of similar cells is now connected in series with a wire of the same material and cross section but of length $2L$. The temperature of the wire is raised by the same amount $\Delta T$ in the same time $t$. The value of $N$ is:

The histogens are classified on the basis of