The Washington Board of Realtors has adopted a multiple listing service for its members and their clients and has contracted with PRC Electronics to provide computer services for the exchanges of property listings between offices. At least 28 realtor firms in the District are participating in the service that has been available in other area realtor jurisdictions for some years.

The Majorie Webster Junior College property near Rock Creek Park in the upper Northwest area west of 16th Street has been sold for $2.6 million to the federal government, which plans to use it as offices and classroom facilities for the National Fire Prevention and Control Administration. Donald A. Butler of the Carey Winston Co. handled the transaction for the sellers.

Rose Associates of New York is considering building a convention hotel in the Pentagon City area in south Arlington. The company recently purchased the 116-acre tract from the heirs of Morris Cafritz and Charles H. Tompkins. A Metro stop already is serving the site bounded by Army-Navy Drive and Route I-95 and 15th Street.

A new guide list and booklet to aid persons in evalauating the purchase of a condominium or co-operative apartment are being made available by the area chapter of the Property Management Association. Copies of the booklet and rating guide are available for $2.50 from PMA. 8811 Colesville Rd., Suite, 255. Silver Spring 20910. For information, call 588-8668.

A real estate workshop for prospective home owners will be presented at 7 p.m. Wednesday at the Manor Club north of Wheaton by Flaherty, Inc., Realtors. Persons desiring to attend may register by calling 946-3900.

James H. Kimberly of Palm Beach, Fla., has listed the 170-acre Gray Fox Farm on the Corsica River near Easton, Md., for $850,000 with the firm of Walsh & Benson in Easton.