Answer: (3)
Medeleev arranged elements in order of increasing atomic weight and similar properties
He noticed that similar elements were grouped together by using this.
Answer:second law of thermodynamics
Explanation:the second law of thermodynamics states that the total entropy of an isolated system can never decrease over time and is constant if only if all processes are reversible.
It produces nitrogen gas and water
4NH3+3O2+heat 2N2+6H 2O
For radioactive decay, we can relate current amount, initial amount, decay constant and time using:
N = No x exp(-λt)
Half-life = ln(2)/λ
λ = ln(2) / 5730
N/No = 80% = 0.8
0.8 = exp( -ln(2)/5730 x t)
t = 1844 years
<h3><u>Answer;</u></h3>
True
<h3><u>Explanation</u>;</h3>
- The molecule NH3 contains all single bonds.
- NH3 has a three single covalent bond among its nitrogen and hydrogen atoms,because one valence electron of each of three atom of hydrogen is shared with three electron.
- There are three covalent bonds are in NH3 . Each hydrogen make a single bond with nitrogen and there is also a pair of electron which is unpaired from nitrogen.
