Which proteinaceous pigment controls light-dependent activities in plants?

The resistance of a bulb filament is $100 \ \Omega$ at a temperature of $100 \ ^oC$. If its temperature coefficient of resistance is $0.005 \ ^oC^{-1}$,at what temperature $(^oC)$ will its resistance become $200 \ \Omega$?

The angle between the lines whose direction cosines satisfy the equations $l+m+n=0$ and $l^2+m^2-n^2=0$ is

Phloem loading is related to:

$A$ compound $(A)$ is used in the preparation of washing soda to recover ammonia in the Solvay process. When $CO_2$ is bubbled through an aqueous solution of $(A)$,the solution turns milky. It is also used in whitewashing due to its disinfectant nature. What is the chemical formula of $(A)$?

The coils of a step-down transformer have $500$ and $5000$ turns. In the primary coil,an $AC$ of $4 \, A$ at $2200 \, V$ is sent. The value of the current and potential difference in the secondary coil will be: