Which of the following groups of algae do not have eukaryotic organization?

The central fringe of the interference pattern produced by light of wavelength $6000 \, \mathring{A}$ is found to shift to the position of the $4^{th}$ bright fringe after a glass plate of refractive index $1.5$ is introduced. The thickness of the glass plate would be ........ $\mu m$.

The centre of mass of three particles of masses $1 ~kg, 2 ~kg$ and $3 ~kg$ is at $(2,2,2)$. The position of the fourth mass of $4 ~kg$ to be placed in the system so that the new centre of mass is at $(0,0,0)$ is:

$A$ horizontal force of $10\,N$ is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and wall is $0.2$. The weight of the block is ........ $N$.

The transfer of energy from organism to organism in a natural community establishes

$A$ centigrade and a Fahrenheit thermometer are dipped in boiling water. The temperature is lowered until the Fahrenheit thermometer registers $140^{\circ}F$. What is the fall in temperature in $^{\circ}C$ as registered by the centigrade thermometer?