Answer:
20 electrons
A neutral atom with atomic number 20 will have 20 electrons.
The atomic number is, by definiton, the number of protons in an atom's nucleus but for a neutral atom it's also equal to the number of electrons. Each element has a different, unique number of protons that determines its identity.
Explanation:
Tc-99m<span> is a </span>metastable isomer<span> of </span>Tc-99. It finds widespread applications in <span>medical diagnostic procedures.
</span>
Tc-99 is also a radioactive element. It's half-life is 2,11,000 years. Upon radioactive decay, it emits beta particles and gets converted into stable compound Ruthenium-99
This process of radioactive decay is shown below.
99 43Tc → 99 44Ru + 0 -1e
(stable) (β particle)
Following are important constant that used in present calculations
Heat of fusion of H2O = 334 J/g
<span>Heat of vaporization of H2O = 2257 J/g </span>
<span>Heat capacity of H2O = 4.18 J/gK
</span>
Now, energy required for melting of ICE = <span> 334 X 5.25 = 1753.5 J .......(1)
Energy required for raising </span><span>the temperature water from 0 oC to 100 oC = 4.18 X 5.25 X 100 = 2195.18 J .............. (2)
</span>Lastly, energy required for boiling water = <span> 2257X 5.25 = 11849.25 J ......(3)
</span><span>
Thus, total heat energy required for entire process = (1) + (2) + (3)
= 1753.5 + 2195.18 + 11849.25
= </span><span>15797.93 J
</span><span> = 15.8 kJ
</span><span>Thus, 15797.93 J of energy is needed to boil 5.25 grams of ice.</span>
