Natural gas is a mixture of .......

Which of the following is not tetrahedral?

In polymeric $(BeCl_2)_n$,there are

In which one of the following do male and female gametophytes not have a free-living independent existence?

If $P_1$ and $P_2$ are two points on the ellipse $\frac{x^2}{4} + y^2 = 1$ such that the tangents at these points are parallel to the chord joining the points $(0, 1)$ and $(2, 0)$,then the distance between $P_1$ and $P_2$ is:

Which of the following is known as a fluid connective tissue?