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Calculate the number of neutrons present in 120 grams of calcium phosphate. |
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Answer» Answer: (i) Total number of electrons PRESENT in 1 methane molecule =6+4=10. Total number of electrons RESENT in 1 mole of methane =10×6.023×10 23 =6.023×10 24 electrons. The number of neutrons is equal to the difference in the MASS number and atomic number. It is equal to $$\d isplaystyle 14-6=8 $$. (ii)(a) The number of neutrons present in 7 mg of C-14 is 14 6.023×10 23 ×8
×7×10 10−3 =2.4088×10 21 neutrons. (b) Total mass of neutrons in 7 mg of C-14 is 2.4088×10 21 ×1.675×10 −27 4.035×10 −6 kg. (iii)(a)Number of protons present in 1 molecule of ammonia =7+3=10. Number of molecules present in 34 mg of ammonia is 17 6.023×10 23 ×34×10 −3
=1.2044×10 21 . Total number of protons present in 34 mg of ammonia=10×1.2044×10 21 =1.2044×10 22
(b) Total mass of protons present in 34 mg of ammonia at STP is 1.6726×10 −27 ×1.204×10 22 =2.0138×10 −5 kg. When temperature and pressure are changed, there is no difference in the answer. |
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