Lawyers and some defendents in the corruption trial of Maryland Gov. Marvin Mandel were plunged into a mood of gloom today by questions sent out to the judge by jurors in the first communication in six days of deliberation.

There was open talk for the first time of conviction and possible imprisonment from defendants who had studiously maintained an optimistic face until now. "Sure," said defendant William Rodgers, gulping, "go ahead and talk about it (prison). I'm prepared for the worst. I've talked about it with my family."

W. Dale Hess, another codefendant who had previously seemed buoyant about this chances, confided that he had "never been optimistic."

None of them was really able to say what the jury was discussing or when it would reach its verdict. But the questions asked were the first vague indication of its thinking.

Two of the questions "assumed there is a scheme' (as alleged in the indictment) and that certain people are in it," said Arnold M. Weiner, Mandel's lawyer. They "indicate that some or all of the jurors are believing in the guilt of some or all of the defendants," he said.

The jurors made their inquiry last night at 5:30 but U.S. District Judge Robert L. Taylor did not report it until this morning, at a open hearing with attorneys from both sides attending.

"If there were a scheme and all six men (Mandel and the five codefendants) are found guilty of one mail fraud count, are all guilty on all 20 mail fraud counts?" began the note, which was addressed "Dear Sir" and signed with a "thank you" by jury foreman Howard O. Davis.

Judge Taylor's response to that question was "no," but the fact that the jurors' question seemed to suggest that all the defendants might be found guilty of at least one count disturbed the lawyers and defendants.

The second question was: "If there were a scheme, and, for example, we find that a defendant came into the scheme some time after its inception, is he guilty of all things prior to the time he entered the scheme?" Taylor first answered yes but later changed his response to "no."

The third question was the only halfway optimistic omen for the defendants."Does acquittal, as well as conviction, require a unanimous vote?" the jury asked. "We ask this question because of the assumption of innocence until guilt is proven." The judge answered "yes" to this question.

The final request was for clarification of technical aspects of the law.

Judge Taylor scheduled a meeting of a lawyers for 9 a.m. Wednesday, and although observers speculated that there were additional jury questions to be discussed, Taylor would not comment.

Gov. Mandel is charged in a 23-count indictment with participating is an alleged scheme to defraud the citizens of Maryland by promoting legislation that brought profits to a racetrack secretly owned by his friends and codefendants. In return, the indictment charges. Mandel allegedly received some $350,000 worth of favors from the same men: Hess, Harry and William A. Rodgers, Irvin Kevens and Ernest N. Cory Jr.

Despite the levels of nervous anticipation reached on previous days of the verdict wait, attorneys and defendants appeared today to have reached a higher state of excitement.

Mandel himself called his fellow defendant William Rodgers and Hess to 25th floor hotel suite after he heard the news about the note. Mandel's attorney, Weiner, said that he had reported only substance of the note to the governor without any elaboration about its implication.

The mention of all six defendants in the first question was also troubling to some attorneys since the implication to them was that if one defendant is convicted all the others also will be found guilty.

In their final arguments attorneys fo Kovens, William Rodgers and Cory all tried to separate their clients from the other defendants. They hoped that a scheme would not be established and that their clients' roles in the alleged scheme would therefore be disproved.

Hess and William Rodgers were be only defendants in the courtroom or the hearing, and afterward they feigned optimism when a gaggle of reporters greeted them outside the building.

But in the relative privacy of a booth in the hotel coffee shop, they soberly reassessed the implication of the note with William Rodgers' attorney, Michael E. Marr.

As Marr explained what kind of sentences they might expect with guilty verdicts. Hess twisted the tine of a fork and Rodgers drummed a knife nervously on the table. Marr said that while the defendants "face exposure to 140 years" in prison (five years on each of '0 mail fraud counts and 20 years on each of two racketeering charges), "realistically, it should be under five."

The lawyer went on to talk about a "split sentence," saying that the judged could "for example order a sentence of five years but give probation on the condition that you serve 30 to 60 days in a county jail."

Hess interjected, "Yes, that's what J. Walter Jones got - three years knocked down to 90 days" (in connection with the investigation of former Vice President Spiro T. Agnew).

Federal procedure, Marr explained, dictates that the defendant "has a right to be sentenced within 60 days - that would be mid-October." At that point, Rodgers attempted to clear his throat and as his eyes met Hess' the two men appeared shaken, and dropped their eyes to the table.

The judge told the lawyers that the questions were "the most intelligent . . . I believe I have received from a jury dealing with such technical questions of law."

Despite the anticipation, there was still room for humor among the lawyers. At his 56th birthday celebration at a nearby restaurant, William G. Hundley. Hess' lawyer, said he had "one wish. If they reach a verdict today. I want it backdated."

That was a reference to a letter allegedly backdated by Hess to show that a $15,000 payment to Mandel was actually money owed the governor for legal services and not a bribe, as prosecutors have alleged.