A and B are the two solid substances. On heating they directly changes into gaseous state without undergoing liquid state. Name these two substances, and by what name this process is called?

When a solid changes to directly gaseous state, the process is called

What is the reason for a substance to change from solid to liquid state ?

The process in which a substance changes directly from solid to gaseous form and vice-versa is called……..

Statement A : The change which can be reversed to get the original state of substance is called Reversible change.Statement B:The change in which original state of the substance cannot be obtained is called Irreversible change.

The substance 'X' normally exist in a physical state which ca flow easily but does not fill its vessel completely. It also turns dry copper sulphate to blue. When substance'X. is cooled excessively, It changes into a substance'y' which has a fixed shape and fixed volume. If, the substance 'x' is heated strongly., it changes into substance'z' which has neither a fixed shape not a fixed volume. Name the process by which'x' can be convertewd to 'y' ?

What is the substance that is heated in the china dish ? What is the process that the compound undergoes ? Write two lines about it .

The substance 'X' normally exist in a physical state which ca flow easily but does not fill its vessel completely. It also turns dry copper sulphate to blue. When substance'X. is cooled excessively, It changes into a substance'y' which has a fixed shape and fixed volume. If, the substance 'x' is heated strongly., it changes into substance'z' which has neither a fixed shape not a fixed volume. name the substances 'x', 'y' and 'z'.

The substance 'X' normally exist in a physical state which ca flow easily but does not fill its vessel completely. It also turns dry copper sulphate to blue. When substance'X. is cooled excessively, It changes into a substance'y' which has a fixed shape and fixed volume. If, the substance 'x' is heated strongly., it changes into substance'z' which has neither a fixed shape not a fixed volume. What is the process of conversion of 'x' into 'z' known as?