In tissue culture experiments,leaf mesophyll cells are put in a culture medium to form callus. This phenomenon may be called as:

What is the composition of the white enamel of our teeth?

$Saccharomyces\, cerevisiae$ is used in the production of......

Which of the following has the maximum nucleophilicity?

Which artery is absent in a frog?

The air density at Mount Everest is less than that at sea level. Mountaineers find that for one trip lasting a few hours,the extra oxygen needed corresponds to $30,000 \ cc$ at sea level (pressure $1 \ atm$,temperature $27^{\circ}C$). Assuming that the temperature around Mount Everest is $-73^{\circ}C$ and that the oxygen cylinder has a capacity of $5.2 \ L$,the pressure at which $O_2$ must be filled in the cylinder is ..... $atm$.