Acontainer holds a pure sample of a radioactive substance with a half-life of 2 hours. which of the following statements are true?

a) after 1 hour, less than 50 % of the original atoms in the container will have decayed.
b) after 1 hour, more than 50 % of the original atoms in the container will have decayed.
c) after 2 hours, 50 % of the original atoms in the container will have decayed.
d) after 4 hours, 25 % of the original atoms will have decayed.
e) after 4 hours, the total number of atoms in the container will be reduced by 75 %.

C, because a half-life is the amount of time it takes for half the atoms to decay.

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: