Best Answer
C) is the best description, although a scientific theory is not necessarily a "fact". They are, however, based on evidence.
A) is complete garbage.
B) is a good description of a scientific "law"- something that predicts how a certain event will occur without explaining why this is (for instance, the law of gravity accurately describes the gravitational forces between two bodies, but does not explain why these forces are there).
D) is a scientific "hypothesis"- an explanation for an observed phenomena that is yet to be proven.
Answer:
Explanation:
exothermic reactions are the reactions which involve the release of energy.
the energy released can be of any forms ,for example heat,light .
all the combustion reactions are exothermic reactions
Answer:
116 g
Explanation:
From the question given above, the following data were obtained:
Number of mole of calcium = 2.9 moles
Mass of calcium =.?
The mole and mass of a substance are related according to the following formula:
Mole = mass / molar mass
With the above formula, we can obtain the mass of calcium. This can be obtained as follow:
Number of mole of calcium = 2.9 moles
Molar mass of calcium = 40 g/mol
Mass of calcium =.?
Mole = mass / molar mass
2.9 = mass of calcium / 40
Cross multiply
Mass of calcium = 2.9 × 40
Mass of calcium = 116 g
Therefore, the mass of 2.9 moles of calcium is 116 g.
Increase in kinetic energy as well as energy loss to the surroundings in the form of heat ( negligible)
Density (d) which is the quotient when mass (m) is divided by volume (v) is usually reported in terms of g/mL.
d = m /v
Substituting the known values,
d = (1.62 kg) x (1000 g/ 1 kg) / (205 mL)
The answer would be approximately equal to 7.9 g/mL.