Between 1858 and 1920, Mars was thought by many, including some scientists, to be very similar to Earth, only drier with a thick atmosphere, similar axial tilt, orbit and seasons as well as a Martian civilization that had built great Martian canals.
Answer:
Assume that you move one end of a rope up and down just once to generate a wave in the rope. How long will take the wave to travel down the rope to the other end? It depends on the speed of the wave.
Sodium fluoride- to brush teeth
Citric acid- orange juice for breakfast
Sodium hydroxide- cleaning agent
Gay-Lussac's law: 
=
We need to convert temperature from Celsius to Kelvin
-55 C = 218 K
30 C = 303 K
V2 = V1*T2 / T1 = 0.550 *303 / 218 = 0.764 l
Hydrogen only has 1 electron so not A.
Barium has 2 valence electrons so answers B!
