Most suitable method of introducing alien $DNA$ into a plant cell is

$A$ flask of volume $10^3 \text{ cc}$ is completely filled with mercury at $0 \ ^\circ\text{C}$. The coefficient of cubical expansion of mercury is $180 \times 10^{-6} / ^\circ\text{C}$ and that of glass is $40 \times 10^{-6} / ^\circ\text{C}$. If the flask is now placed in boiling water at $100 \ ^\circ\text{C}$,how much mercury (in $\text{cc}$) will overflow?

How many tripeptides can be prepared by linking the amino acids glycine,alanine and phenylalanine?

In algae,the photosynthetic pigments are present in

The minimum deviation produced by a hollow prism filled with a certain liquid is found to be $30^o$. The angle of refraction is also found to be $30^o$. The refractive index of the liquid is

The maximum and minimum melting points of the first and second transition series elements,respectively,are obtained with: