I Have one form and applied some validations on Pan_no Item on it.
When user make a new entry validations applied on pan_no item works properly,
But when in query mode user update pan_no validations applied on pan_no doesn't work, while validations applied on other item works properly.
I using oracle forms 10g
I presume that you mean 'during enter-query' mode.
And the answer is that you are correct, validation does not operate during this phase.
The general approach is to use list items or LOVs to get valid data into form fields for filtering the results of queries.