I believe the answer is A the 1st one
Answer:

Explanation:
1. Calculate the decay constant
The integrated rate law for radioactive decay is 1

where
A₀ and A_t are the counts at t = 0 and t
k is the radioactive decay constant

2. Calculate the half-life

The half-life for decay is
.
The correct answer would be D: Physical properties can be observed without changing the identity of a substance
If, in a peptide chain, there were 85 amino acids each joined by peptide bonds, there would only be 1 N-terminus group that would be present. The N-terminus group is always the start of the chain of a amino acid chain or a protein or a polypeptide. It refers to the free amine group present that is located at the end part of the chain. So, that no matter how many amino acids in a chain there would always be only one N-terminus group.
Answer:
A. Cu^+2(aq)cathode ---> Cu^+2(aq)anode
Explanation:
Electrolysis is the process in which current is passed through a solution thereby causing a chemical change at the anode and cathode. Copper is being purified using electrolysis by using impure copper at the anode and pure copper at the cathode. This pure and impure copper are placed in a copper(ii)sulfate electrolyte solution and dc current is made to pass through it. The resulting changes at the anode and cathode are given by the equation:
cathode: Cu²⁺ + 2e⁻ ⇒ Cu
anode: Cu ⇒ Cu²⁺ + 2e⁻