What is the function of the algal component in a lichen?

What is the molar solubility of $Ag_2CO_3$ $(K_{sp} = 4 \times 10^{-13})$ in $0.1 \ M \ Na_2CO_3$ solution?

$A$ double slit experiment is performed by using light of wavelength $6000\,\mathring{A}$. If the distance of the screen is $1\,m$ and the slits are $0.1\,cm$ apart,then calculate the angular position of the $10^{th}$ bright fringe.

Which of the following $0.05 \, M$ aqueous solution will have the lowest freezing point?

The logic gate equivalent to the circuit shown in the figure is

In order to double the frequency of the fundamental note emitted by a stretched string,the length is reduced to $\frac{3}{4}$ of the original length and the tension is changed. The factor by which the tension is to be changed is