The set of all real numbers under the usual multiplication operation is not a group since
A.  multiplication is not a binary operation 
B.  multiplication is not associative 
C.  identity element does not exist 
D.  zero has no inverse 
Option: D Explanation : Click on Discuss to view users comments. zuhaib said: (5:10pm on Friday 24th February 2017)
multiplication identity is '1' and additive edentity is '0'..thats right answer is '0' has no invers
Kith said: (5:23pm on Wednesday 22nd March 2017)
R{0} is a group under multiplication

If (G, .) is a group such that (ab) 1 = a1b1, ∀ a, b ∈ G, then G is a/an
A.  commutative semi group 
B.  abelian group 
C.  nonabelian group 
D.  None of these 

If (G, .) is a group such that a2 = e, ∀a ∈ G, then G is
A.  semi group 
B.  abelian group 
C.  nonabelian group 
D.  none of these 
Option: B Explanation : Click on Discuss to view users comments. 
The inverse of  i in the multiplicative group, {1,  1, i ,  i} is
A.  1 
B.  1 
C.  i 
D.  i 
Option: C Explanation : Click on Discuss to view users comments. Amit kumar said: (7:57pm on Sunday 26th November 2017)
As we know a.a^1 =a^1.a = e And 1 is the multiplicative identity element As (i Ã—i )=1So i is the inverse element of i
