An HII region is Group of answer choices one of the large and cold molecular clouds where we see star formation going on a place where there is mostly neutral hydrogen whose spectral lines we observe a cloud of dark dust, which absorbs much of the starlight coming from behind it a cloud of complex molecules, such as alcohol and formaldehyde a zone around a hot star where hydrogen atoms are ionized

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force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

im srry but ur wrong the answer is d a smooth rock, some red dirt, and an empty bird's nest.