Q.

The relation R in the set of natural numbers N defined as R={(x,y):y=x+5 and x<4} is:

1 reflexive  
2 symmetric  
3 transitive  
4 None of these  

Ans.

(4)

Ans.    None of these

Explanation:

R={(1,6),(2,7),(3,8)}

∵   (6,6)∉R

⇒R is not reflexive.

For   (2,7)∈R

⇒    (2,7)∈R but (7,2)∉R

⇒R is not symmetric.

Clearly, R is not transitive.

(Since, there is no pair in R such that (x,y) and (y,z)∈R, then (x,z)∈R)

⇒   R is not an equivalence relation.