Consider the combustion of methane, CH4 :

An electron that is in the highest energy level of an atom and determines the atom's chemical properties is called a(n)

ss7ja [257]

The answer is C: Valence electron

3 0

3 years ago

Can someone help me please??

Xelga [282]

41) Answer is: the average atomic mass of chromium is 52.056.

Ar(⁵⁰Cr) = 50.

ω(⁵⁰Cr) = 4.34% ÷ 100%.

ω(⁵⁰Cr) = 0.0434; relative abundance of chromium-50.

Average mass can calculate by summary of percentege of each isotope.

Ar(Cr) = Ar(⁵⁰Cr) · ω(⁵⁰Cr) + Ar(⁵²Cr) · ω(⁵²Cr) + Ar(⁵³Cr) · ω(⁵³Cr) + Ar(⁵⁴Cr) · ω(⁵⁴Cr).

Ar(Cr)= 50 · 0.0434 + 52 · 0.8379 + 53 · 0.095 + 54 · 0.0237.

Ar(Cr) = 2.17 + 43.571 + 5.035 + 1.280

Ar(Cr) = 52.056.

42) Chlorine has atomic number 17, it means it has 17 protons and 17 electrons.

Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.

Chloride is negative ion of chlorine. Chloride is formed when chlorine gain one lectron.

Chloride anion has 17 protons and 18 electrons (like argon-noble gas).

The electron configuration for the chloride ion: ₁₇Cl⁻ 1s²2s²2p⁶3s²3p⁶.

43) Anwser is: the percent by mass of hydrogen in aspirin is 4.48%.

% calculate by atomic mass of element multiply number of that element in molecule divided by molecular mass of molecule.

Ar(H) = 1.008; the relative atomic mass of hydrogen atom.

Mr(C₉H₈O₄) = 9 · Ar(C) + 8 · Ar(H) + 4 · Ar(O).

Mr(C₉H₈O₄) = 180.157.

ω(H)= 8 · Ar(H) ÷ Mr(C₉H₈O₄) · 100%.

ω(H) = 8 · 1.008 ÷ 180.157 · 100%.

ω(H) = 4.48 %.

44) Balanced chemical reaction:

Cd(NO₃)₂ + 2NH₄Cl → CdCl₂ + 2NH₄NO₃.

This chemical reaction is double displacement reaction - cations (Cd²⁺ and NH₄⁺) and anions (NO₃⁻ and Cl⁻) of the two reactants switch places and form two new compounds.

Cd(NO₃)₂ is cadmium nitrate.

NH₄Cl is amonium chloride.

CdCl₂ is cadmium chloride.

NH₄NO₃ is ammonium nitrate.

4 0

4 years ago

Explain why the equation ( x - 4 ) ^2 - 28 =8 has two solutions. Then solve the equation to find the solutions. Show your work.

algol13

Taking into account the discriminant and quadratic formula:

As Δ> 0 the function has two real roots or solutions.
The solutions are x1= 10 and x2= -2.

<h3 />

Zeros or solutions of a function

The points where a polynomial function crosses the axis of the independent term (x) represent the so-called zeros of the function.

That is, the zeros represent the roots of the polynomial equation that is obtained by making f(x)=0.

In summary, the roots or zeros of the quadratic function are those values of x for which the expression is equal to 0. Graphically, the roots correspond to the abscissa of the points where the parabola intersects the x-axis.

<h3>Discriminant</h3>

The function f(x) = ax² + bx + c

with a, b, c real numbers and a ≠ 0, is a function quadratic expressed in its polynomial form (It is so called because the function is expressed by a polynomial).

The following expression is called discriminant:

Δ= b²- 4×a×c

The discriminant determines the amount of roots or solutions of the function.

Then:

If Δ <0 the function has no real roots and its graph does not intersect the x-axis.
If Δ> 0 the function has two real roots and its graph intersects the x-axis at two points.
If Δ = 0 the function has a real root and its graph intersects the x-axis at a single point that coincides with its vertex. In this case the function is said to have a double root.

<h3 /><h3>Amount of solutions of function (x - 4)² - 28 =8</h3>

The function (x - 4)² - 28 =8 can be expressed as:

(x - 4)² - 28 -8= 0

(x - 4)² - 36= 0

x²- 8x + 16 - 36= 0

x²- 8x - 20= 0

Being: