190. According to Boolean algebra which of the following relation is not valid?

A. X =1

B.X+Y=Y+X

C.X.Y=Y.X

D. X + (Y+Z)= (X +Y)+Z

191. According to Boolean algebra which of the following relation is not valid?

A. X (X + Y)= X

B. (X + Y) (X + Z) = X + YZ

C.X+XY=X+Y

D.XY+ YZ + YZ=XYZ

192. According to Boolean algebra 1 + A + B+ C is equal to

A.A+B+C

B.ABC

C. 1 +ABC

D.1

193. (A + B + A B) is the same as

A.0

B.1

C.C

D. T

194. Three Boolean operators are

A. OR, NOT, AND

B. OR, NOR, NAND

C. NOT, NOR, NAND

D. None of the above

195. The truth table given below is for

A. AND gate

B. NAND gate

C. OR gate

D. NOR gate

196. Positive logic in a logic circuit is one in which

A. logic 0 and 1 are reprennted by 0 and positive voltage respectively

B. logic 0 and 1 are represented by negative and positive voltage respectively

C. logic 0 voltage level is higher than logic 1 voltage level

D. logic 0 voltage level is lower than logicl voltage level

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