I believe it's the second option. 2 or more elements joined together such that the elements have lost their individual identity in favour of a new set of properties.
The molar mass of the unknown compound is calculated as follows
let the unknown gas be represented by letter Y
Rate of C2F4/ rate of Y = sqrt of molar mass of gas Y/ molar mass of C2F4
= (4.6 x10^-6/ 5.8 x10^-6) = sqrt of Y/ 100
remove the square root sign by squaring in both side
(4.6 x 10^-6 / 5.8 x10^-6)^2 = Y/100
= 0.629 =Y/100
multiply both side by 100
Y= 62.9 is the molar mass of unknown gas
Every 2 million years the amount is halved
0 million = 200g
2 million = 200g/2 = 100g
4 million = 100g/2 = 50g
The scientist thought that the
atom was the smallest particle in the universe is John Dalton. He established
the atomic theory which consists of five; elements are made of extremely small
particles called atoms, atoms of different element have different sizes, mass
and physic – chemical properties, atoms cannot be divided further, destroyed or
created, atoms can combine to form compounds and in chemical reaction, atoms
can be combined, separated or rearranged.
According to Raoult's law, Vapor pressure is directly proportional to the mole fraction of the solution. As 1.0 M CaF2 has least moles here, it has lowest vapor pressure.
In short, Your Answer would be Option D
Hope this helps!