Astudent is measuring the effect of an electric circuit on a compass and he is testing to see if increasing the current will cause the compass needle to change its direction faster he does one trral using a 9-volt battery and another trial using a 1.5 volt battery he takes accurate data based on good experimental design which would improve his experiment

see earlier

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.