What is the evidence that suggests the past and present existence ...

[mpobi80]

What is the evidence that suggests the past and present existence of surface water on Mars?
 
  What will be an ideal response?

Question 2

Consider the following statement, and explain whether or not it is sensible: The universe is between 10 and 16 billion light-years old.
 
  What will be an ideal response?

[Viet Thy]

Answer to Question 1

Runoff channels from old rivers and outflow channels from catastrophic flooding in the distant past. Recent mudflows down the sides of some canyons and crater walls suggest occasional eruptions of liquid water persist to this day, as imaged by the Global Surveyor. The Rovers in 2004 also found clear evidence of sedimentary rocks formed under water at both the landing sites, on opposite sides of the globe.

Answer to Question 2

This statement does not make sense because it uses the term light-year as a length of time, rather than as a distance.

[mpobi80]

Both answers were spot on, thank you once again

[Viet Thy]

Great! Please up vote