Verbal Reasoning - Mental Ability Questions

Son of Y's Son — Grandson; Brother of Ts grandson — C's grandson. 

The alphabets are coded as follows :

$$\begin{gathered} C H A R O L M E \\ 4 5 1 6 9 3 2 7 \end{gathered}$$

R is coded as 6,

E as 7,
A as 1  and
L as 3.
So, the code for REAL is 6713

Error is in the first part of the sentence. 'Whole' is used with singular nouns.
The correct sentence is - 'All Northern states in India are reeling under the devastating of the drought.

4 is father of 1 and grandfather of 6. So, 1 is father of 6. Thus, 4 and 1 are the two fathers.
3 is the sister of 6. So, 3 is the daughter of 1. Since there is only one mother, it is evident that 5 is the wife of 1 and hence the mother of  3 and 6. So, 2 is brother of 1. There are three brothers. So, 6 is the brother of 3. Hence, 2 and 1 are brothers. 6 is the brother of 3. So, three brothers are 1, 2, 6.

Iron with specific gravity less than that of mercury but more than that of water, floats in the former but gets immersed in the second 

PSRQ --> {16, 19, 18, 17} - next 3 alphabets of "P" is written in reverse order
SVUT --> {19, 22, 21, 20} - next 3 alphabets of "S" is written in reverse order

MNPO --> {13, 14, 16, 15}

KNML --> {11, 14, 13, 12} - next 3 alphabets of "K" is written in reverse order

Except "MNPO", others are not in consecutive order.