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3 years ago

A ___________________ is a combination of two or more atoms that are held together by covalent bonds.

Chemistry

2 answers:

Andre45 [30]3 years ago

3 0

The answer is Molecule

frosja888 [35]3 years ago

3 0

The answer is molecules.

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A solution of a concentration of H+ (10-4 M) has a pH of

Alecsey [184]

Answer:

pH = 4

Explanation:

pH = -log[H⁺] = -log(10⁻⁴) = -(-4) = 4

3 0

3 years ago

How many atoms are in 8 gram of helium

Yuri [45]

There are two atoms..............

5 0

3 years ago

A 50.0 50.0 mL solution of 0.127 0.127 M KOH KOH is titrated with 0.254 0.254 M HCl HCl. Calculate the pH of the solution after

Brilliant_brown [7]

Answer:

Explanation:

THE CORECT QUESTION

A 50.0 mL solution of 0.127 M KOH is titrated with 0.254 M HCl. Calculate the pH of the solution after the addition of each of the given amounts of HCl.

SOLUTION

Get the concentration of the HCl first using titration formula

CA X V A / CB VB = NA/ NB

Equation of reation; KOH + HCl => KCl + H2O

CA = 0.254 M

CB = 0.127

VA = 1/0.254 = 3.937

CA (after the addition) = 0.127 x 50 / 3.937

= 1.612 M

But pH = - Log[hydrogen ion]

= -log 1.612

8 0

3 years ago

Agree or disagree that a scientific theory can be modified provide evidence along!!!!!!!

oksano4ka [1.4K]

Answer:

I agree.

Explanation:

7 0

3 years ago

Naturally occurring element X exists in three isotopic forms: X-28 (27.979 amu, 92.21% abundance), X-29 (28.976 amu 4.70% abunda

bezimeni [28]

Answer: The average atomic mass of X is 28.09 amu

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For isotope 1:

Mass of isotope 1 = 27.979 amu

Percentage abundance of isotope 1 = 92.21 %

Fractional abundance of isotope 1 = 0.9212

For isotope 2:

Mass of isotope 2 = 28.976 amu

Percentage abundance of isotope 2 = 4.70 %

Fractional abundance of isotope 2 = 0.0470

For isotope 3:

Mass of isotope 3 = 29.974 amu

Percentage abundance of isotope 3 = 3.09 %

Fractional abundance of isotope 3 = 0.0309

Putting values in equation 1, we get:

$\text{Average atomic mass of X}=[(27.979\times 0.9212)+(28.976\times 0.0470)+(29.974\times 0.0309)]$

$\text{Average atomic mass of X}=28.09amu$

Hence, the average atomic mass of X is 28.09 amu

4 0

3 years ago