Asolution with a hydroxide ion concentration of 4.15 × 10-4 m is and has a hydrogen ion concentration of a solution with a hydroxide ion concentration of 4.15 × 10-4 m is and has a hydrogen ion concentration of basic, 2.41 × 10-10 m acidic, 2.41 × 10-10 m acidic, 2.41 × 10-11 m basic, 2.41 × 10-11 m

Solution with hydroxide ion concentration 4.15 x 10⁻⁴ M, has a pOH value of ;
pOH = -log (4.15x10⁻⁴)
pOH = 3.38
pH + pOH = 14
Therefore pH = 14 - 3.38 = 10.62
when pH> 7 the solution is basic .
since pH is known we can calculate hydrogen ion concentration 
[H⁺]= antilog (-10.62)
[H⁺] = 2.4 x 10⁻¹¹ M
answer is basic, 2.41 × 10-11 m

The answer is c) pyrite

The answer is 1.82 j/g°c