Why was becquerel’s experiment a first step in discovering radioactivity?

a. it showed that a substance could phosphoresce when it was not exposed to light.

b. it showed that the substance that was used by becquerel could phosphoresce.

c. it showed that a substance could constantly emit radiation even if it was not exposed to light.

d. it showed that a substance emitted radiation when it
was exposed to light.

C.

The findings occurred after a radioactive substance was left in a closed space, inaccessible to sunlight, with some photographic plates. The conclusion drawn from this was that emission of radiation can occur without sunlight, contrary to the prior belief. 

The answer is false because: gravitational force is independent of medium and depends only on the masses of the two objects and the distance between them

Electron equations of the given changes are as follow,a)                              cu      →      cu⁺²  + 2e⁻b)                              mg⁺²  +  2 e⁻      →      mgc)                              cl⁻    →      cl  +  1e⁻d)                              s  +  2 e⁻    →      s²⁻e)                                o²⁻      →      o  +  2 e⁻f)                              p  +  3 e⁻    →      p³⁻g)                              fe²⁺    →      fe³⁺  + 1 e⁻h)                              s²⁻    →      s⁴⁺  +  6 e⁻