What is the process of transferring cell cultures from an old medium to a new medium called?

The slopes of the lines represented by $x^2+2 h x y+2 y^2=0$ are in the ratio $1:2$,then $h$ is equal to:

$1.00 \ g$ of a non-electrolyte solute (molar mass $250 \ g \ mol^{-1}$) is dissolved in $51.2 \ g$ of benzene. If the freezing point depression constant of benzene is $5.12 \ K \ kg \ mol^{-1}$,then the freezing point of benzene decreases by ...... $K$.

Which reaction involves a change in the electron pair geometry for the underlined atom?

The half-life of $Ra^{226}$ is $1620$ years. Calculate the number of atoms that decay in one second in $1 \ g$ of radium (Avogadro number $= 6.023 \times 10^{23}$).

The coefficient of static friction,$\mu_s$ between block $A$ of mass $2\,kg$ and the table as shown in the figure is $0.2$. What would be the maximum mass value of block $B$ so that the two blocks do not move (in $,kg$)? The string and the pulley are assumed to be smooth and massless. $(g = 10\,m/s^2)$