1 calorie is equal to 4.184 Joules.
Answer: 1.06 kg
Explanation:
Density is defined as the mass contained per unit volume.

Given :
Density of mercury = 
volume of cylinder = volume of mercury = 
where r = radius of cylinder = 
h= height = 25.0 cm
Putting in the values we get:
volume of mercury =
(1kg=1000g)
Thus mass of mercury required to fill a hollow cylinder having an inner diameter of 2.00 cm to a height of 25.0 cm is 1.06 kg.
The answer is B. darker; cooler the dark spots give off less energy then the rest of the sun.
Hope this helps
The answer to this question would be: false
Autopsies are performed to the body that didn't die from a natural cause or known disease. This will include homicide or suicide. Some case that suspected to be suicide would be a homicide that was covered by the criminal. In this case, the body is examined for any unnatural or suspicious sign that might be caused by the killer. Autopsy also needed in a malpractice case.
Answer:
17.65 grams of O2 are needed for a complete reaction.
Explanation:
You know the reaction:
4 NH₃ + 5 O₂ --------> 4 NO + 6 H₂O
First you must know the mass that reacts by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction). For that you must first know the reacting mass of each compound. You know the values of the atomic mass of each element that form the compounds:
- N: 14 g/mol
- H: 1 g/mol
- O: 16 g/mol
So, the molar mass of the compounds in the reaction is:
- NH₃: 14 g/mol + 3*1 g/mol= 17 g/mol
- O₂: 2*16 g/mol= 32 g/mol
- NO: 14 g/mol + 16 g/mol= 30 g/mol
- H₂O: 2*1 g/mol + 16 g/mol= 18 g/mol
By stoichiometry, they react and occur in moles:
- NH₃: 4 moles
- O₂: 5 moles
- NO: 4 moles
- H₂O: 6 moles
Then in mass, by stoichiomatry they react and occur:
- NH₃: 4 moles*17 g/mol= 68 g
- O₂: 5 moles*32 g/mol= 160 g
- NO: 4 moles*30 g/mol= 120 g
- H₂O: 6 moles*18 g/mol= 108 g
Now to calculate the necessary mass of O₂ for a complete reaction, the rule of three is applied as follows: if by stoichiometry 68 g of NH₃ react with 160 g of O₂, 7.5 g of NH₃ with how many grams of O₂ will it react?

mass of O₂≅17.65 g
<u><em>17.65 grams of O2 are needed for a complete reaction.</em></u>