The answer is:
B)They are in the same group because they have similar chemical properties, but they are in different periods because they have very different atomic numbers.
The explanation:
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties.
A period is a horizontal row of elements on the periodic table. For example, the elements sodium ( Na ) and magnesium ( Mg ) are both in period 3. The elements astatine ( At ) and radon ( Rn ) are both in period 6.
Answer:
Part a)

Part b)

So density of atmosphere at Martian Surface is very less than the density at Earth.
Explanation:
Part a)
As per ideal gas equation we know that

here we know that Martian atmosphere is equivalent to that of carbon
so we will have


now we will have


Part b)
Now for the earth surface the density of air is given for


so we will have



So density of atmosphere at Martian Surface is very less than the density at Earth.
Answer:
a) Yes because spiderman isn’t part of the system (the train), so he exerts an external force on the system, causing it to slow. The sign is negative because the train is slowing negative.
b) The train was initially moving, so it had kinetic energy, the energy of movement. There isn’t the same amount anymore because spiderman did work onto the train. Work is defined by the change of kinetic energy of the system, so the train didn’t have the same amount of that type of energy at the end.
I hope this helps! :)