1)

Let  a:∼(pr)(qs)   and 

b: (ps)(qr) .If the truth  values of p and q are true and that of r and s are false, then the truth values of a and b  be respectively...........


A) F, F

B) T, T

C) T, F

D) F,T

Answer:

Option A

Explanation:

 Key Idea  Use   pq=∼pq

 and    pq=(pq)(pq)

 Given,  p,qT and r,sF

     a:∼(pr)(qs)

 ≡∼(TT)(FF)

≡∼(T)(F)

FF=F

 and  b: (ps)(qr)

((ps)(qr))((ps)(qr))

pq(pq)(pq)

((TF)(TF))((TF)(TF))

(FF)(TT)

 FTF