In lines 10-19 of Kennedy's inaugural address, the tone could best be described as what?
Without seeing the copy of Kennedy's address with line numbers that this question is referring to, it is impossible to know exactly what lines 10-19 actually are. But it seems likely, given the way the speech is laid out, that the question is referring to the passage that begins:
Let the word go forth from this time and place, to friend and foe alike, that the torch has been passed to a new generation of Americans--born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage--and unwilling to witness or permit the slow undoing of those human rights to which this nation has always been committed, and to which we are committed today at home and around the world.
In this passage, Kennedy is asserting the determination of what we have come to know as the "World War II generation" (of which he himself was a member) to uphold the values they remembered fighting for in the 1940s and in the early years of the Cold War. He goes on to say that the United States will "meet any price" and "bear any hardship" to ensure the "survival and success of liberty." The tone of these lines is resolute, even bellicose or warlike in places. Kennedy is positioning himself in the same way he had during the election of 1960--as a tough anti-Communist who is willing to do almost anything to promote what he saw as an agenda of freedom around the world. Of course, the address was being delivered to the American people, but with his strident tone, Kennedy was sending a message to Nikita Khrushchev and the Soviet Union as well.