What is the undifferentiated mass of cells in tissue culture called?

Consider a metal sphere of radius $R$ that is cut in two parts along a plane whose minimum distance from the sphere's centre is $h$. The sphere is uniformly charged by a total electric charge $Q$. The minimum force necessary to hold the two parts of the sphere together is:

Who classified all Bryophytes into three classes?

Chemical $A$ is used for water softening to remove temporary hardness. $A$ reacts with sodium carbonate to generate caustic soda. When $CO_2$ is bubbled through $A$,it turns cloudy,what is $A$?

An eight-digit number divisible by $9$ is to be formed using digits from $0$ to $9$ without repeating the digits. The number of ways in which this can be done is: (in $(7!)$)

The solution of $x dx + y dy = x^2 y dy - x y^2 dx$ is