To which group does the plant shown in the given figure belong?

In a $\triangle ABC$,if $\frac{\cos A}{a} = \frac{\cos B}{b} = \frac{\cos C}{c}$,then $\triangle ABC$ is

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Blue-green algae	$(I)$ Spirogyra
$(B)$ Unicellular algae	$(II)$ Nostoc
$(C)$ Filamentous algae	$(III)$ Volvox
$(D)$ Colonial algae	$(IV)$ Chlamydomonas

Four capacitors marked with their capacitances and breakdown voltages are connected as shown in the figure. Find the maximum $EMF$ of the source such that no capacitor breaks down. (in $kV$)

In the reaction,$C_2H_5OC_2H_5 + CO \xrightarrow[150^{\circ}C, 500 \text{ atm pressure}]{BF_3} X$. What is $X$?

An ideal refrigerator has a freezer at a temperature of $-13^{\circ}C$. The coefficient of performance of the refrigerator is $5$. The temperature of the air (to which heat is rejected) will be: