The value of $\sqrt{42+\sqrt{42+\sqrt{42+\ldots}}}$ is equal to:

An electron moves with speed $2 \times 10^5 \ m/s$ along the positive $x$-direction in the presence of a magnetic field of induction $B = (\hat{i} + 4\hat{j} - 3\hat{k}) \ T$. The magnitude of the force experienced by the electron in newtons is (Charge on the electron $= 1.6 \times 10^{-19} \ C$)

Which air pollutant is responsible for the Bhopal gas tragedy?

Two blocks of masses $1 ~kg$ and $2 ~kg$ are connected by a metal wire going over a smooth pulley as shown in the figure. The breaking stress of the metal is $2 \times 10^9 ~N/m^2$. What should be the minimum radius of the wire used if it is not to break? Take $g = 10 ~m/s^2$.

Which of the following is the only taxonomic category that has a real existence?

$A$ body,thrown upwards with some velocity,reaches a maximum height of $50 \ m$. Another body with double the mass thrown up with double the initial velocity will reach a maximum height of $.......... \ m$.