Which of the following noble gases does not have an octet of electrons in its outermost shell?

An atomic power nuclear reactor can deliver $300 \ MW$. The energy released due to the fission of each nucleus of a uranium atom $^{238}U$ is $170 \ MeV$. The number of uranium atoms fissioned per hour will be:

The intensity of radiation emitted by the Sun has its maximum value at a wavelength of $510 \ nm$ and that emitted by the North Star has the maximum value at $350 \ nm$. If these stars behave like black bodies,then the ratio of the surface temperature of the Sun and the North Star is

On closing an open organ pipe from one end,it is noticed that the frequency of the third harmonic is $50 ~Hz$ more than the fundamental frequency of vibration in the open organ pipe. The fundamental frequency of the open organ pipe is (in $~Hz$)

Let $P(3, 2, 6)$ be a point in space and $Q$ be a point on the line $\vec{r} = (\hat{i} - \hat{j} + 2\hat{k}) + \mu(-3\hat{i} + \hat{j} + 5\hat{k})$. Then the value of $\mu$ for which the vector $\vec{PQ}$ is parallel to the plane $x - 4y + 3z = 1$ is:

The solution of $\cos y + (x \sin y - 1) \frac{dy}{dx} = 0$ is