MY COLLECTION

1)  If a 0.1mm paper is folded 100 times then what will be the thickness
     of it after 100 folding?

2) Would anyone know the shortest sentence in the English language
    that has every letter of the alphabet?

3) How many times are the hands of a clock at right angle
    in a day?

4) You have three jars that hold max 19, 13 and 7 liters of water
     respectively. 13 and 7 litre jars are full of water and 19 litre jar
     is empty (so total 20 litres of water).

     You can pour water between jars and I want two jars with 10
     litres of water (i.e, 10, 10, 0 from 0, 13, 7)

5) There is a safe with a 5 digit number as the key. The 4th
    digit is 4 greater than the second digit, while the 3rd digit
    is 3 less than the 2nd digit. The 1st digit is thrice the
    last digit. There are 3 pairs in the number whose sum is 11.

                  Find the number.