instruction:
In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 
question:
A red giant burns mass. This mass creates high core temperatures. The mass decreases. The red giant can no longer fuse the carbon and oxygen in its center. The gravity of the star can no longer hold the outside layers. The layers break away. Only the inner core remains. This inner core is known as a white dwarf. 
answer:
How is a white dwarf star formed?


question:
Rainwater picks up carbon dioxide from the air. Rainwater goes into soil. Water with carbon dioxide percolates through soil. The water becomes a weak acid. The water dissolves limestone. Caves form where the limestone was dissolved. 
answer:
How do caves form?


question:
Rock begins as magma from a volcano. The magma cools. Crystals form and the magma become igneous rocks. The igneous rocks break down into sediment. Become sedimentary rocks. If subjected to heat and/or pressure from plate-tectonic activity the sedimentary rocks become metamorphic rock. The metamorphic rocks melt. Become magma again. 
answer:

What happens during the rock cycle