Why are clouds look white

Which of the following is evidence to the past existence of glaciers?

You have been tasked with sorting the rock samples shown into three categories, with two rocks in each category. what attribute would you use to sort these rocks? which rocks would be in each category? rocks: obsidian, coquina limestone, granite, soapstone,pumice, and gneiss.

When you start from a given set of rules and conditions and determine what must be true you are using blank reasoning