Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Some meteorites are made of iron and nickel and are thought to be very similar to the core of the earth.
Some meteorites are made of iron and nickel and are thought to be very similar to what part of the earth?

Unlike ammonia, oxygen cannot be liquefied at room temperature because its critical temperature is below room temperature.
Unlike ammonia, oxygen cannot be liquefied at room temperature because its what is below room temperature?

Change in momentum in an object is equivalent to impulse .
Change in momentum in an object is equivalent to what other measurement?