Answer : The mass of
required is 18.238 grams.
Explanation : Given,
Mass of
= 83.10 g
Molar mass of
= 146 g/mole
Molar mass of
= 256.52 g/mole
The balanced chemical reaction is,

First we have to determine the moles of
.

Now we have to determine the moles of
.
From the balanced chemical reaction we conclude that,
As, 8 moles of
produced from 1 mole of 
So, 0.569 moles of
produced from
mole of 
Now we have to determine the mass of
.


Therefore, the mass of
required is 18.238 grams.
Answer:
We need 226 grams of FeS
Explanation:
Step 1: Data given
Mass of FeCl2 = 326 grams
Molar mass FeCl2 = 126.75 g/mol
Step 2: The balanced equation
FeS + 2 HCl → H2S + FeCl2
Step 3: Calculate moles FeCl2
Moles FeCl2 = 326 grams / 126.75 grams
Moles FeCl2 = 2.57 moles
Step 4: Calculate moles FeS needed
For 1 mol H2S and 1 mol FeCl2 produced, we need 1 mol FeS and 2 moles HCl
For 2.57 moles FeCl2 we need 2.57 moles FeS
Step 5: Calculate mass FeS
Mass FeS = 2.57 moles * 87.92 g/mol
Mass FeS = 226 grams FeS
We need 226 grams of FeS
Answer:
B extinction
Explanation:
as the species does not exist any more, the species is extinct, therefore making the pictured fossil of an extinct species
hope this helps
The various atomic masses of the same element are called<u> isotopes</u>. They have the same number of protons but different number of neutrons.
Answer:
The effective nuclear charge for a valence electron in oxygen atom: 
Explanation:
Effective nuclear charge
is the net nuclear charge experienced by the electron in a given atom. It is always less than the actual charge of the nucleus [Z], due to shielding by electrons in the inner shells.
<em>It is equal to the difference between the actual nuclear charge or the atomic number (Z) and the shielding constant (s). </em>

<u>For an oxygen atom</u>-
Electron configuration: (1s²) (2s² 2p⁴)
<em>The atomic number (actual nuclear charge): </em>Z = 8
The shielding constant (s) for a valence electron can be calculated by using the Slater's rules:
⇒ s = 5 × 0.35 + 2 × 0.85 = 1.75 + 1.7 = 3.45
<u><em>Therefore, the effective nuclear charge for a valence electron in oxygen atom is:</em></u>

<u>Therefore, the effective nuclear charge for a valence electron in oxygen atom:</u> 