A law requiring developers converting apartment buildings to condominiums to pay up to $750 in relocation expenses to any tenant who is found to be in financial need was enacted yesterday by the Montgomery Country Council.

But the council rejected a proposal to require that apartment renters and country agencies acting on their behalf be given the first opportunity to buy their buildings if condominum conversion is undertaken. A committee had told the council that a voluntary program in which developers are urged to give tenants the opportunity to purchase their units is working.

Conversion of rental units has become a source of major controversy in the country, as about 10,400 apartment and town house units have been changed to condominiums or cooperatives in the last decade. One concern is that some renters will be forced out of the country by conversion.

The relocation expense law, enacted as an emergency measure, goes into effect immediately. It empowers Country Executive Charles W. Gilchrist do issue regulations for determining df a tenant's need is sufficient to justify the payment.

As introduced by its sponsor, council member Elizabeth Scull, the legislation contained both the recolation expense and the first -- right --to --purchase requirements. Her full proposal failed by one vote. Scull was the only member to vote against the amended measure that went on to be approved.

Although he voted for the amended bill, council member Scott Fosler said he thought that deleting the provision giving tenants and country agencies the right to buy "gutted" the measure.

"To say it's gutted implies it had guts to start with," replied Council President Neal Potter before the vote. He described the defeated provision as a minor proposal "to give people the privilege for a few weeks to see if they could swing a deal."

One problem noted by some council members is that the cost of a project escalates once its owner sells it to a developer planning to convert it to condominiums.

Scull has proposed a measure -- not yet acted on -- that would give tennants and the country the right to purchase a building before it is sold to a converter. That measure also would give tennants the right to commission an independent engineering report and receive a warrantly on major systems.

Country executive Gilchrist had asked the council before yesterday's vote "to support the voluntare approach to the solution" of the conodominium conversion issue, which he called "extremely difficult."

The council's action also followed receipt of a report of a joint government, industry and tenant committee on the voluntary program under which developers are encouraged to give tenants "a minimum 45-day right -- of -- first -- refusal to purchase their units" and offer other assistance to tenants.

The report concluded both that the program is working and that the government's efforts "should shift-away from mandatory intervention in conversions to preservation of the existing rental stock.