Verbal Reasoning - Mental Ability Questions

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?
642 x 6 ÷ 25 + 4 = ?

A prime number between 10 and 50 remains unchanged if its digits are reversed. Then the square of such a number is:

In a row of girls, Shweta is 11th from the right end. Mansi is 14th to the left of Shweta. If Mansi is 12th from the left end, then how many girls are there in the row?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

HK, ? , PQ, TT, XW

If EFMIJ means DELHI, then the last letter of the word got by decoding IQBOS is

In a row of boys, Punit’s position from the left end is 33rd and Ankit’s position from the right end is 25th. After interchanging their position, Punit’s positionbecomes 45th from the left end. How many boys are there in the row?

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

4, 5.2, 6.4, ?, 8.8

The weights of 4 boxes are 100, 70, 50 and 90 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?