Answer:

Explanation
Density can be found by dividing the mass by the volume.

We know the iron sheet has a mass of 28.5 grams and the volume is 3.60 milliliters.

Substitute the values into the formula.

Divide.

Let's round to the nearest thousandth.
The 6 in the ten-thousandth tells us to round the 6 to a 7.

The density of iron is about <u>7.917 grams per milliliter.</u>
Answer:b.CaCl2
Explanation:
A compound is a substance resulting when two or more elements are are chemically bonded together either ionically or covalently in a fixed ratio.
From the given options we can see that the only compound there is CaCl2 which is an ionic compound in the fixed ratio of one calcium ion to two chloride ions.
Other options , Cu,Na and Nd are merely pure substance---Elements
The array will be created with the elements equal to null.
Answer:

Explanation:
You can calculate the entropy change of a reaction by using the standard molar entropies of reactants and products.
The formula is

The equation for the reaction is
C₂H₄(g) + 3O₂(g) ⟶ 2CO₂(g) + 2H₂O(ℓ)
ΔS°/J·K⁻¹mol⁻¹ 219.5 205.0 213.6 69.9
