Fairfax County officials lobbied here today for bicycle trails, the right to impose a 4 per cent sales tax on gasoline, and against an annexation bill County Board Chairman John F. Herrity said could lead to the "balkanization of Fairfax County."

Herrity and Supervisor James M. Scott (D-Providence), began their day by button-holing Del. Richard L. Saslaw (D-Fairfax), as he was moving between four simultaneous committee meetings to voice their opposition to the "balkanization" bill that would allow communities more easily to incorporate into towns.

Herrity and Scott said they feared that independent Fairfax City is contemplating annexing a large tract of county land and that the annexation bill would facilitate this move.

Saslaw said he "would probably vote against the bill" but told the Fairfax officials he thought "some of your fears are not well-founded. There's no way Fairfax City is going to seize Fairfax County." he said.

That's exactly what Fairfax City officials say. City Councilman Walter L. Stephens said the Council "is not interest in annexing any land."

Martha V. Pennino (D-Centreville), said she had gotten "five different interpretations" of the futuristic" bill. "How do I explain it to the people back in Fairfax County?" she said. "Do I give them five different interpretations?"

The annexation bill would put an end to the current moratorium on creation of new towns in Virginia and set new guidelines for towns becoming cities and for towns becoming cities and for cities annexing parts of counties. Some communities within Fairfax County occasionally have discussed the possiblity of forming themselves into towns in order to gain a new tax base for services they feel they are not getting from the county, according to Del. Raymond E. Vickey (D-Fairfax).

Fairfax officials also lobbied hard for a bill that would allow the county to impose a 4 per cent gasoline tax to help pay for Metro costs. The county wants a tax that can be implemented without the unanimous consent of all Northern Viginia jurisdictions. The bill, passed last year but was not implemented because it was opposed by Fairfax City. It would bring Fairfax County an additional $4 million according to Supervisor Joseph Alexander.

Finally, a resolution sponsored by Del. Raymond E. Vickery (D-Fairfax), urging public utility companies to give easy access to bikers and hikers on their properties, was passed out of committee today, unanimously, to the House after supervisor Pennino spoke in favor of the measure.

The resolution should facilitate the opening of the old Washington and Old Dominion Railroad line between Vienna and Falls Church, now used as a right of way by the Virginia Electric and Power Co., for bicycle riders.

Pennino said the General Assembly "has not always been sensitive to these kind of things. "We have been encouraged by the reaction and responses of the Northern Virginia delegates," she said.

In other action, the House of Delegates today gave initial approval to a bill sponsored by Del. Ira M. Lechner (D-Arlington) that would allow Virginia drug stores to sell prescription drugs in bottles without so-called child-proof caps that make opening the bottles difficult for children. The bill will come up for a final vote in the House on Wednesday and forwarded to the Senate.

The House also gave initial approval to two bills sponsored by Del. Thomas W. Moss (D-Norfolk).

One bill would force the State Water Control Board to drop a requirement that small pleasure boats be equiped with sewage "holding tanks." The other bill is aimed at prohibiting merchants from misrepresenting goods offered for sale and empowers local prosecutors to obtain court orders to stop unfair practices.

By vote of 74 to 18 the House approved and sent to the Senate a measure offered by Del. John L. Melnick (D-Arlington) that would extend to the dependents of victims of crime possible compensation from a new fund established last year for crime victims.

The House also gave initial approval to a bill Godwin vetoed last year that would end the use of noknock search warrants in Virginia. Under present law, Virginia police officers do not have to announce their presence before entering a dwelling to execute a search warrant.