Mark the correct alternative in each of the following:

Let * be a binary operation on N defined by a * b = a + b + 10 for all a, b ∈ N. The identity element for * in N is

Mark the correct alternative in each of the following:

A binary operation * on Z defined by a * b = 3a + b for all a, b ∈ Z, is

Mark the correct alternative in each of the following:

Let * be a binary operation on Q⁺ defined by for all a, b ∈ Q⁺. The inverse of 0.1 is

Mark the correct alternative in each of the following:

Consider the binary operation * defined on Q - {1} by the rule a * b = a + b – ab for all a, b ∈ Q – {1}. The identity element in Q – {1} is

Mark the correct alternative in each of the following:

For the binary operation * defined on R – {1} by the rule a * b = a + b + ab for all a, b ∈ R – {1}, the inverse of a is