Acceleration can be defined as the change of speed in an instant of time, that is

Here,
Final velocity
Initial velocity
Change in time
From this expression we will calculate the requested values replacing the variables in each of the given terms
PART A) The values under this condition are:



Replacing,


PART B ) The values under this condition are:



Replacing,


Therefore the acceleration in the second time interval is
PART C) The values under this condition are:



Replacing,


Matter is defined as anything that has mass and occupies space, it may be classified into three states, solid, liquids or gases. Molecules is the smallest particle of an element that has the chemical properties of the element or the compound. it contains two or more atoms that are joined together. A pure substance is a matter that has distinct properties and a composition that does not vary from sample to sample. Thus the correct answer is C
Its a solar cell. Photo voltaic Cell is also known as a solar cell.