Q.

Graph between log k and 1T [k is rate constant (s-1) and T the temperature (K)] is a straight line. OX = 5, θ=tan-1(12.303). Hence -Ea will be

1 2.303×2 cal  
2 22.303 cal  
3 2 cal  
4 2.3032 cal  

Ans.

(3)

logk=logA-Ea2.303RT    (y=c+mx)

Slope=-Ea2.303R=12.303  (given)  (tanθ=12.303)

-Ea=2.303R×slope

=2.303×R2.303=R=2 cal