Answer:

Explanation:
We are given the volumes and concentrations of two reactants, so this is a limiting reactant problem.
We know that we will need moles, so, lets assemble all the data in one place.
Cu²⁺ + 4NH₃ ⟶ Cu(NH₃)₄²⁺
V/mL: 3.00 7.00
c/mol·L⁻¹: 0.050 0.20
1. Identify the limiting reactant
(a) Calculate the moles of each reactant

(b) Calculate the moles of Cu(NH₃)₄²⁺ that can be formed from each reactant
(i) From Cu²⁺

(ii) From NH₃

NH₃ is the limiting reactant, because it forms fewer moles of the complex ion.
(c) Concentration of the complex ion

MgCl2 because it is the only option in which a metal appears with a nonmetal. In this case, the metal transfers electrons to the nonmental because the metal has a lower ionization energy.
Answer:
C
Explanation:
an index fossil is a fossil from a very short-lived, geographically widespread species known to exist during a specific interval of geological time.
There are 2 significant figures. All numbers in a whole number are significant.