The hottest would be the O type and the coolest is M
Answer:

Explanation:
Assuming that cars 4 and 5 have same mass so that the momentum
P=mv where m is mass and v is velocity hence
Momentum=0+2mv+3mv=5mv
The final mass is 2m+3m=5m
From aw of conservation of momentum
hence 
Therefore, the speed is 
The answer is C. ionic compounds, compared to another hard compound which is the covalent bond, the structure of the ionic compound is lattice or crystalline in form thus less room for imperfections on its structure compared to the latter choices.
Answer:
B. twice as much kinetic energy
Explanation:
Lets take the mass of the first marble =2 m
the mass of the second marble = m
We know that velocity of particle does not depends on their mass that is the velocity of both mass will be same after dropping from the roof.
We know that kinetic energy of a mass is given as

Kinetic energy for heavier mass

Kinetic energy for light mass

KE=2 KE '
Form above two equation we can say that ,the kinetic energy for the heavier mass is twice the lighter mass.
Therefore the answer will be B.