Answer:
The richer source of calcium is fluorite.
Explanation:
Percentage of element in compound :

1. Dolomite is a carbonate of magnesium and calcium:
Given mass of dolomite = 7.81 g
Mass of calcium present in given mass of dolomite = 1.70 g
Percentage of calcium in Dolomite:

2. Fluorite is a mineral of calcium and fluorine:
Given mass of fluorite = 2.76 g
Mass of fluorine present in given mass of fluorite = 1.34 g
Percentage of fluorine in fluorite :

Percentage of calcium in fluorite = 100% - 48.55 % = 51.45%
Percentage of calcium in fluorite > Percentage of calcium in Dolomite
51.455 > 21.77%
So, the richer source of calcium is fluorite.
Answer: I. The number of molecules is conserved.
III. Atoms are neither created nor destroyed
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products formed must be equal to the mass of reactants taken.
In order to get the same mass on both sides, the atoms of each element must be balanced on both sides of the chemical equation.
For example: 
Thus in the reactants, there are 4 atoms of hydrogen , 2 atoms of oxygen and 2 atoms of sodium.Thus there will be 4 atoms of hydrogen, 2 atoms of oxygen and 2 atoms of sodium in the product as well.
The main properties of uranium-238 are as follows,
- The uranium-238 have orthorhombic crystal structure.
- The physical state of uranium-238 is solid.
- The uranium-238 have acid base properties.
- The uranium-238 have hard and silver white metal.
- The natural abundance of uranium-238 is 99%
The Atomic mass and atomic weight of uranium-238
- The atomic number of uranium-238 is 92
- The atomic weight of uranium-238 is 238.02
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Answer: radio wave frequencies have longer wavelengths and smaller
Energies per photon
Answer:
Answer is: 20 min.Bismuth 214 decay mode to lead is beta minus decay and alpha decay.Beta decay is radioactive decay in which a beta ray and a neutrino are emitted from an atomic nucleus.
There are two types of beta decay: beta minus and beta plus. In beta minus decay, neutron is converted to a proton and an electron and an electron.Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.
Explanation: