A petition to sell, mortgage, exchange, pledge or lease any real or personal property shall set forth the reasons for the application and describe the property involved. It may apply for different authority as to separate parts of the property; or it may apply in the alternative for authority to sell, mortgage, exchange, pledge or lease. Whenever it is for the best interests of the estate, real and personal property of the estate may be sold, mortgaged, exchanged, pledged or leased as a unit.