Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).
The most abundant of all of the isotopes of an element will be the one who's mass the mass of element is closest to. In this case, the mass of atomic carbon is closest to the mass of carbon-12.
Thus, Carbon-12 is the most abundant isotope.
Answer:
Explanation:
There are some radioactive nuclides can be used to measure time on an archeological scale. One is the best example of this is radiocarbon dating. This process is based on the ratio of caebon-14 to carbon-12 in the atmosphere which is relatively constant.
The half time of C-14 5730 years
Carbon-14 is a radioactive nucleus. It has a half-life of 5730 years.
All living tissues like plants and animal absorbed carbon-12 along with carbon-14 with same ratio of caebon-14 to carbon-12 in the atmosphere.
Carbon-14 dating is based on the ratio of carbon-14 to carbon-12 in the atmosphere which is relatively constant
Answer: Option (b) is the correct answer.
Explanation:
Vitamins which are soluble in water are known as water-soluble vitamins. And, vitamins which remain insoluble in water are known as water-insoluble vitamins.
Water-soluble vitamins are able to be easily excreted by the human body through urine. For example, vitamin C and vitamin B-complex are water soluble vitamins.
Thus, we can conclude that water-soluble vitamins are easily excreted in the urine.
