9Be + 2H -> 10B + 1n

The equation 9Be + 2H -> 10B + 1n is unbalanced. Assuming the intended reaction is 9Be + 2H -> 10B + 1n (where 2H represents deuterium), then: Atomic numbers: 4 + 1 = 5 (left); 5 + 0 = 5 (right). Mass numbers: 9 + 2 = 11 (left); 10 + 1 = 11 (right). The reaction is balanced.