What does below rebus means ?

Can anyone tell me a word in the English dictionary which has a silent 'z'?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

What is the longest word in the dictionary?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

A man has to get a fox, a chicken, and a sack of corn across a river.

He has a rowboat, and it can only carry him and one other thing.
If the fox and the chicken are left together, the fox will eat the chicken.
If the chicken and the corn are left together, the chicken will eat the corn.

How does the man do it?

At a Society election for president, precisely 963 votes were cast.
There is a total of 4 candidates that participate in the election.

The winning candidate exceeds the opponents by 53, 79 and 105 votes.

How many votes do each candidate gets?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

The answer I give is yes, but what I mean is no. What was the question?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?