Select the missing number?

If 10$25 = 8, 12$25 = 10 then what is the value of 14$53 = ?

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?
24 x 6 - 8 + 2 = ?

If ETHANOL is coded as HWKDQRO, then how will MIX be coded as?

From the given alternative words, select the word which cannot be formed using the letters of the given word:
ECCENTRICITY

The weights of 4 boxes are 30, 40, 50 and 100 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes and in a combination a box can be used only once?

Nasir's birthday is on Thursday 18th May. On what day of the week will be Rehan's Birthday in the same year if Rehan was born on 19th August?

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.
49, 64, ?, 100, 121