The moons phases are caused by A. Eclipse of sun

B. Planets moving across the face of the moon

C. The alignment of the Earth, moon, and sun

D. The alignment of the planets.

Please help me

The first-order reaction a→2b+c has rate constant 0.538 s−1. if the initial concentration of a is 0.867 mol l−1, what is the half-life of the reaction in seconds? remember to use correct significant figures in your answer (round your answer to the nearest hundredth). do not include units in your response.