Magnesium (mg) reacts explosively with oxygen (o2) gas . which of these elements is most likely to react with oxygen in a similar way ?

Beryllium, Calcium, Strontium, Barium and Radium.

You can choose any of them

If your taking the same quiz as me the correct answer is calcium (Ca) because it is in the same category as magnesium (Mg) otherwise refer to the other answer if you want all other elements that react with (O2) oxygen.

second mirror gathers light from a faraway object and reflects it to another mirror. - a.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.