The equation of the pair of lines joining the origin to the points of intersection of $x^2+y^2=9$ and $x+y=3$ is:

$A$ $x : 1$ molar mixture of $He$ and $CH_4$ is contained in a vessel at $20 \ bar$ pressure. Due to a hole in the vessel,the gas mixture leaks out. If the composition of the mixture effusing out initially is $8 : 1$,then the value of $x$ will be

Which role is played by Lactobacillus in our stomach?

The equation $16 x^2+y^2+8 x y-74 x-78 y+212=0$ represents:

The mirror image of the point $P(1, 2, 3)$ in a plane is $P'\left(-\frac{7}{3}, -\frac{4}{3}, -\frac{1}{3}\right)$. Which of the following points lies on this plane?

Which one of the following removes temporary hardness of water?