Answer:
The answer is D (contains index fossils)
Explanation:
A sample of tennantite with mass of 2370 g contains 19.23 mol Cu.
You must make the following conversions:
Mass of tennantite → moles of tennantite → moles of Cu
<em>Step 1</em>. Calculate the <em>moles of tennantite</em> (Tn)
The <em>ideal </em>chemical formula of Tn is Cu_12As_4S_13.
Molar mass = (12×63.55 + 4×74.92 + 13×32.06) g/mol
= (762.60 + 299.68 + 416.78) g/mol = 1479.06 g/mol
Moles of Tn = 2370 g Tn × (1 mol Tn/1479.06 g Tn) = <em>1.60 24 mol Tn
</em>
<em>Step 2</em>. Calculate the <em>moles of Cu</em>
Moles of Cu = 1.6024 mol Tn × (12 mol Cu/1 mol Tn) = 19.23 mol Cu
Answer is C
A synthesis reaction looks like this:
A+ B → AB
Answer:
7 Valence Electrons.
Explanation:
The Valence electrons are referred to as the number of electrons in the outermost shell of an atom.
When given the electronic configuration, the valence can be calculated by adding the superscript of the hugest number coefficient.
The highest number coefficient in this electronc cnfiguration is 2. The sum of it's superscript is 2 (in 2s²) and 5 ( in 2p⁵). That is 2 + 5 = 7
How to test the answer?
The atom given has 9 electrons ( 2 + 2 + 5).
The K shell is being occupied by 2 electrons, the next shell; M shell which can occupy maximum of 8 electrons is being occupied by 7 electrons ( 9 - 7). And in this atom, the M shell is the outermost shell.