The main aim of this article is to study non-singular version of Moser-Trudinger and Adams-Moser-Trudinger inequalities and the singular version of Moser-Trudinger equality in the Cartesian product of Sobolev spaces. As an application of these inequalities, we study a system of Kirchhoff equations with exponential non-linearity of Choquard type.In this connection, in 1960's, Pohozaev [24] and Trudinger [26] independently answered the question using the above function with φ(t) = exp(|t| n n−1 ) − 1. Later on,in [20], Moser improved the result by proving the following inequality which is popularly known as the Moser-Trudinger inequality:MT Theorem 1.1. For n ≥ 2, Ω ⊂ R n is a bounded domain and u ∈ W 1,n 0 (Ω),If κ > κ α,n,m then the above supremum is infinite (i.e. κ α,n,m is sharp).