What is true of a reaction that has reached equilibrium? a)The rate of the forward reaction is less than the rate of the reverse reaction.

b)The rate of the forward reaction is greater than the rate of the reverse reaction.

c)reaction rates of the forward and reverse reactions are equa

d)The reaction rate is zero.

THE EMPIRICAL FORMULA OF THE COMPOUND IS Ir Se2

Explanation:

Iridium = 16.7 g

Selenium = 10.3 g

Total mass = 16.7 + 10.3 = 27 g

To calculate the empirical formula, we first calculate the percentage com[position of the individual elements.

Percentage composition of iridium = 16.7 / 27 * 100 = 61.85 %

Percentage composition of selenium = 10.3 / 27 * 100 = 38.15 %

Next is to divide the percentage composition of each element by their respective molecular masses

Molecular mass of iridium = 192 g/mol

Molecular mass of selenium = 79g/mol

Iridium = 61.85 / 192 =  0.3221

Selenium = 38.15 / 79 = 0.4829

Next is to divide the values by the smaller of the two values

Iridium = 0.3221 / 0.3221 = 1

Selenium = 0.4829 / 0.3221 = 1.5

Next is to round up the values to a whole number

Iridium = 1

Selenium = 2

The empirical formula therefore is Ir Se2