What is a bacteriophage?

$A$ circular coil of area $200 ~cm^2$ and $50$ turns is rotating about its vertical diameter with an angular speed of $40 ~rad/s$ in a uniform horizontal magnetic field of magnitude $2 \times 10^{-2} ~T$. The maximum emf induced in the coil is (in $~V$)

In which of the following reactions does $H_2O_2$ act as a reducing agent?

Rearrange the following ($I$ to $IV$) in the order of increasing masses:
$I$. $0.5$ mole of $O_3$
$II$. $0.5$ g-atoms of oxygen
$III$. $3.011 \times 10^{23}$ molecules of $O_2$
$IV$. $5.6$ $L$ of $CO_2$ at $STP$

If $R$ is the radius of the Earth and $g$ is the acceleration due to gravity on the Earth's surface,then the mean density of the Earth is ..........

In which of the following reactions is $H_2O_2$ acting as a reducing agent?