Given the balanced equation representing the reaction between methane and oxygen: according to this equation, what is the mole ratio of oxygen to methane?.

The reaction considered here is

a CH₄ + b O₂   ⇒   c CO₂ + d H₂O

where a, b, c, d are unknown coefficients.

To balance the reaction, we want the same number of the same atoms on either side, so

• C : a = c

• H : 4a = 2d

• O : 2b = 2c + d

Suppose a = 1; then c = 1 and d = 2 and b = 2. So the balanced reaction is

CH₄ + 2 O₂   ⇒   CO₂ + 2 H₂O

and this means the mole ratio of oxygen to methane is 2 to 1.

Theorem: If two chords intersect within a circle, then the product of the lengths of the segments (parts) of one chord is equal to the product of the lengths of the segments of the other chord.

In your case this theorem sounds as

Solve this equation:

correct choice is C.