The element with the nlx notation of 5d2 in the periodic table is hafnium with a symbol of hf. It is a chemical element and has an atomic number 72. H<span>afnium chemically resembles zirconium and is found in many zirconium minerals but it is a complete contrast of zirconium which is also chemically similar to hafnium.</span>
N₀ is the number of C-14 atoms per kg of carbon in the original sample at time = Os when its carbon was of the same kind as that present in the atmosphere today. After time ts, due to radioactive decay, the number of C-14 atoms per kg of carbon is the same sample which has decreased to N. λ is the radioactive decay constant.
Therefore N = N₀e-λt which is the radioactive decay equation,
N₀/N = eλt In (N₀.N= λt. This is the equation 1
The mass of carbon which is present in the sample os mc kg. So the sample has a radioactivity of A/mc decay is/kg. r is the mass of C-14 in original sample at t= 0 per total mass of carbon in a sample which is equal to [(total number of C-14 atoms in the sample at t m=m 0) × ma]/ total mass of carbon in the sample.
Now that the total number of C-14 atoms in the sample at t= 0/ total mass of carbon in sample = N₀ then r = N₀×ma
So N₀ = r/ma. this equation 2.
The activity of the radioactive substance is directly proportional to the number of atoms present at the time.
Activity = A number of decays/ sec = dN/dt = λ(number of atoms of C-14 present at time t) =
λ₁(N×mc). By rearranging we get N = A/(λmc) this is equation 3.
By plugging in equation 2 and 3 and solve t to get
t = 1/λ In (rλmc/m₀A).
Following reactions are involved in present reaction
1) A<span>g+(aq) + Li(s) → Ag(s) + Li+(aq) </span><span>− 384.4kJ
2) </span><span>2Fe(s) + 2Na+(aq) → Fe2+(aq) + 2Na(s) + 392.3kJ
</span>3) <span>2K(s) + 2H2O(l) → 2KOH(aq) +H2(g) −393.1kJ
In above reaction, reaction 1 and 3 has negative value of </span>δh∘f, while reaction 2 has posiyive value of <span>δh∘f. As per the sign convention positive sign indicates that heat is given out during the reaction, while negative sign indicates heat is to be supplied for reaction to occur. In alternative words, product formed in reaction 2 is stable as compared to reactant. Hence, it is thermodynamically favorable. </span>
Answer:
The disadvantages of each of the given model of electron configuration have been mentioned below:
1). Dot Structures - They take up excess space as they do not display the electron distribution in orbitals.
2). Arrow and line diagrams make the counting of electrons and take up too much space.
3). Written Configurations do not display the electron distribution in orbitals and help in lose counting of electrons easily.
Answer:
Explanation:
1. Calculate the moles of Sr(NO₃)₂
2. Calculate the mass of SrNO₃)₂
