A buffer system usually will need a weak acid, like H2CO3, which is carbonic acid, and a strong base, and the only compound that could figure a fairly strong base among the options given is Na2CO3. NH3 and NaHCO3 are weak bases and HF is a strong acid. Therefore the best answer will be letter A
1. The Alpha particle is a helium nucleus, is positively charged & would barely penetrate a piece of paper.<span />
Answer:
Mass = 24.36 g of N₂
Explanation:
The balance chemical equation for the decomposition of NaNO₃ is as follow;
2 NaN₃ → 2 Na + 3 N₂
Step 1: Find moles of N₂ as;
According to equation,
2 moles of NaNO₃ produces = 3 moles of N₂
So,
0.58 moles of NaNO₃ will produce = X moles of N₂
Solving for X,
X = 3 mol × 0.58 mol / 2 mol
X = 0.87 mol of N₂
Step 2: Calculate mass of N₂ as,
Mass = Moles × M.Mass
Mass = 0.87 mol × 28.01 g/mol
Mass = 24.36 g of N₂
Answer: Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.
Explanation:
The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.
