<u>Answer:</u> The correct option is A) They have fixed energy values.
<u>Explanation:</u>
Electron is one of the sub-atomic particle present around the nucleus of an atom which is negatively charged.
In an atomic model, it is assumed that the electron revolves around the nucleus in discrete orbits having fixed energy levels.
These electrons when jumping from one energy level to another, some amount of radiation is either emitted or absorbed.
These fixed energy levels are given by the Bohr model and thus, the electrons are quantized.
Hence, the correct option is A) They have fixed energy values.
Answer: 2948
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Expression for rate law for first order kinetics is given by:
where,
k = rate constant = 
t = age of sample = ?
a = let initial amount of the reactant = 100
a - x = amount left after decay process = 
Thus the fossil is 2948 years old.
I would say the answer is emissions. These are the particles that are not supposed to be present in air but due to the production of different substances from humans daily activities these substances go with the air we breath. Hope this helped.
C. 2Fe2O3 would be the correct answer!
<span>Chemical reaction: CH</span>₃COO⁻(aq) + H⁺(aq) ⇄ CH₃COOH(aq).
H⁺ is from HNO₃: HNO₃ → H⁺ + NO₃⁻.
<span>A buffer can
be defined as a substance that prevents the pH of a solution from changing by
either releasing or absorbing H</span>⁺ in a
solution.
Buffer is a solution
that can resist pH change upon the addition of an acidic or basic components
and it is able to neutralize small amounts of added acid or base, pH of
the solution is relatively stable.
