What is produced when $Mg$ burns in $CO_2$?

If $\overrightarrow{a}=\hat{i}-\hat{j}-\hat{k}$ and $\overrightarrow{b}=\lambda \hat{i}-3 \hat{j}+\hat{k}$ and the orthogonal projection of $\overrightarrow{b}$ on $\overrightarrow{a}$ is $\frac{4}{3}(\hat{i}-\hat{j}-\hat{k})$, then $\lambda$ is equal to

The work function of a metallic surface is $5.01 \ eV$. Photo-electrons are emitted when light of wavelength $2000 \ \mathring{A}$ falls on it. The potential difference applied to stop the fastest photo-electrons is .............. $V$ $[h = 4.14 \times 10^{-15} \ eV \cdot s]$.

$CsBr_3$ contains

Which salt is used as a purgative?

The major product of the following reaction is: