For hundreds of years before the seventeenth century, thinkers explained that sudden appearances of life, such as mold on food or moss on rocks, were caused by "spontaneous generation,” which is the idea that life frequently springs up from non-living material. to the use of scientific experiments, which required repeatable tests, and the invention of the microscope, scientists such as louis pasteur discovered that these appearances of life were actually caused by microscopic organisms in the air that could stick to surfaces and grow into large populations we can see with our eyes. what is shown about scientific theories by the shift in belief of spontaneous generation to the use of other observations to explain where mold and moss come from? theories usually are false. theories are not useful. theories change over time. theories can be completely proven.

C) Theories change over time

Explanation:

A theory is an unproven guess at answering a question that is not a uniform solution. Its just the idea given by by scientists for what is happening and why. It  means over time, people tweak the theory until it fits every possible situation it can be a part of. They are just an idea given by thinkers on the basis of beliefs present at that time. See, theory of spontaneous generation was proposed when science and technology was in its primitive form during early period . Louis Pasteur proved the idea wrong by experiment . Further new theories like panspermia were proposed which might would be proved wrong with development in science and technology.

So it is safe to say that theories change over time and can only be proved true only  with experiment and proper explaining of the facts.

Hope it helps!!!

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

so here is the information for current research:

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