What is obtained from yeast?

The structure of $Cl_2O_7$ is ......

Two persons $A$ and $B$ are located in the $X-Y$ plane at the points $(0,0)$ and $(0,10)$ respectively. (The distances are measured in $MKS$ units). At time $t=0$,they start moving simultaneously with velocities $\overrightarrow{v}_A = 2\hat{j} \text{ m/s}$ and $\overrightarrow{v}_B = 2\hat{i} \text{ m/s}$ respectively. The time after which $A$ and $B$ are at their closest distance is

Two identical blocks $A$ and $B$,each of mass $m$,are placed on a smooth horizontal surface and are connected by a light spring of length $L$ and force constant $k$. $A$ third identical block $C$ of mass $m$ moves along the line joining $A$ and $B$ with velocity $v$ and collides with block $A$. The maximum compression in the spring is:

The pressure of an ideal gas varies with volume as $P = \alpha V$,where $\alpha$ is a constant. One mole of the gas is allowed to undergo expansion such that its volume becomes $m$ times its initial volume. The work done by the gas in the process is

If $x$ is real, then the minimum value of $\frac{x^2-x+1}{x^2+x+1}$ is