The physical description would be soft due to the lava cooling the rock.
On Earth, the period of a pendulum is given by:

where L is the length of the pendulum and

is the gravitational acceleration on Earth.
Similarly, the period of the same pendulum on Mars will be

where

is the gravitational acceleration on Mars.
Therefore, if we want to see how does the period of the pendulum on Mars change compared to the one on Earth, we can do the ratio between the two of them:

Therefore, the period of the pendulum on Mars will be 1.63 times the period on Earth.
False. Acids are actually found in the pH range from 0 to 7 and bases are found from 9 to 14. Meanwhile, 7 and 8 are considered neutral.