What does the cell wall of algae consist of?

$Fe_2Cr_2O_4 + Na_2CO_3 + O_2$ $\xrightarrow{\text{Fusion}} [X]$ $\xrightarrow[H_2O]{H^+} [Y]$ $\xrightarrow{H_2O_2/H^+} [Z]$
Which of the following statements is true for the compounds $[X], [Y]$ and $[Z]$?

The figure shows a system of logic gates. From the study of the truth table,it can be found that to produce a high output $(1)$ at $R$,we must have:

Who discovered lichens?

The cold junction of a thermocouple is maintained at $10\,^{\circ}C$. No thermo $e.m.f.$ is developed when the hot junction is maintained at $530\,^{\circ}C$. The neutral temperature is ................ $^{\circ}C$.

The condition that the roots of $x^3-b x^2+c x-d=0$ are in geometric progression is