Note that
The heating value of standard coal is about 30,080 kJ/kg
1 L of water has a mass of 1.0 kg
The mass of 15 L of water = 15 kg.
The latent heat of vaporization of water is about 2260 kJ/kg,
The energy required to boil 15 L of water is
(2260 kJ/kg)*(15 kg) = 33900 kJ
The mass of coal required to provide this energy is
(33900 kJ)/(30080 kJ/kg) = 1.127 kg
Because 1 kg = 2.205 lb, the mass of coal required is
(1.127 kg)*(2.205 lb/kg) = 2.485 lb
Answer: 2.49 lb (nearest hundredth)
Each natural element has a characteristic light spectrum that helps identify it in samples of unknown substances. Spectroscopy is the practice of examining spectra and comparing them to those of known elements. Using spectroscopy methods, scientists can identify pure substances or compounds and the elements in them.
Rigidity is the inability to bent or be force out of shape while compressibility is the ability to be flattened, pressed or squeezed into a smaller piece.
density is the degree of compactness of a substance.
That would be nuclear fission. This occurs at a rapid level in the Atom Bomb. That is a chain reaction causing an explosion whereas the nuclear fission that occurs in a nuclear reactor is controlled.
Answer:
D. For the atoms lower in the periodic table, the valence electrons are in higher energy levels and farther from the nucleus.
Explanation:
Atomic radius increases down the group because down the group, there an increase in the number of principle energy levels occupied. Now, these higher principal energy levels are made up of orbitals that are larger than the orbitals from the lower energy levels in size.
Therefore, the effect of this is that the greater number of principal energy levels will outweigh the increase in nuclear charge since nuclear charge also increases down the group and this in turn makes the atomic radius to increase as we go down the group.
