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 = ?

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

MEASUREMENT

In a certain code language, “TOLDER” is written as “WSQGIW”. How is “SPIRAL” written in that code language?

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

MAN, ODR, QGV, SJZ, ?

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

RS, WX, BC, ?

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?

S_RTR_ST_T_S

In the following series, one letter is missing as shown by the ?. Select the missing letter from the given options.

N, L, J, H, ?

Which set of letters when sequentially placed at the gaps in the given letter series shall complete it?

j_l_jk_m_kl_