Equitable Life Insurance Co. has acquired an 11-acre site at Tysons Corner for $1.5 million from Leasco Realty Inc. " Theproperty is near the recently completed headquarters of the National Automobile Dealers Association. Equitable, which sold its former office building on Wisconsin Avenue in the District to the Federal National Mortgage Association, is presently leasing space in the Westgate Office Park in McLean.

The D.C. Bankers Association, the Washington Board of Realtors and the Cooperative Housing Association have commissioned a study of mortgage financing for cooperative apartments. Joseph H. Riley, president of the Bankers Association, said banks have difficulty making co-op loans, in part because they are uncertain whether cooperative apartments are adequate collateral to secure those loans. The study was organized in response to a request from D.C. City Councilman David Clarke.

The written examinations for real estate broker and sales agent licenses in the District will be held Tuesday at the Quality Inn, 415 New Jersey Ave. NW, beginning at 8:30 a.m.

Two recreational lakes, surrounded by parks, have been completed in the new town of St. Charles in Charles County, Md. The developer said that the two small lakes will be used for boating and fishing but not swimming.

Better Homes Realty is handling the sales of the brick single houses that Woodside Development, Inc., of McLean, is building in the Burke Lake area of Fairfax County. The houses have three to five bedrooms. Prices begin at $79,000.

Busch Properties, Inc., developer of Kingsmill on the James in the Williamsburg area, has been given an historic preservation award by the Association for Preservation of Virginia Antiquities. Support of archaelogical research at the Kingsmill site was cited.

Energy conservation topics will be featured at the annaul convention of the Building Owners and Managers Association that opens Sunday in Dallas.

The Maryland division of Pulte Home Corp. has opened a subdivision of split-level and two-story houses at Stonegate in the Frederick area. The three-bedroom houses are priced in the mid-$40,000s.