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3 years ago

The majority of the elements essential to life are found in what part of the periodic table?

1 answer:

3 0

The rows in the top third - This group consists of elements like Sodium, Magnesium, Potassium and Calcium on the right and Chlorine, Carbon, Nitrogen and Oxygen on the left.
Sodium and Chlorine are components of salt, a very important compound of our blood, essential for transferring electrical signals from the brain to the rest of the body and vice versa. Calcium is the building block of our bones, while Magnesium and potassium ensure proper functioning of our organs.

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Rewrite each percent as a fraction and decimal 56%

Tasya [4]

I know the decimal is .56 i hope someone knows the fraction
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6 0

3 years ago

Multiple choice-- please help!

kvasek [131]

The rate law for the reaction : r=k.[A]²

<h3>Further explanation</h3>

Given

Reaction

A ⟶ B + C

Required

The rate law

Solution

The rate law is a chemical equation that shows the relationship between reaction rate and the concentration / pressure of the reactants

For the second-order reaction it can be:

1. the square of the concentration of one reactant.

$\tt r=k[A]^2$

2. the product of the concentrations of two reactants.

$\tt r=k[A][B]$

And the reaction should be(for second order) :

2A ⟶ B + C

Thus, for reaction above (reactant consumption rate) :

$\tt r=-\dfrac{\Delta A}{2\Delta t}=k[A]^2$

6 0

3 years ago

Which of the following statements a about scientific hypothesis is false?

Pachacha [2.7K]

Answer:

The false statement from the given statements is option a.

Explanation:

Hypothesis:

A hypothesis is a intelligent guess or prediction to interpret or explain any phenomena.

It is tested through the series of experiments and by number of studies to actually decide whether hypothesis is in agreement with observation and results predicted by it. These prediction are made on basis of limited evidences. It can be false or true.

Theory:

A theory is an in depth explanation behind any physical phenomena which has been tested multiple times through the correct scientific methods and experimentation. It will give same results and observations.

7 0

3 years ago

The concentration of ozone in ground-level air can be determined by allowing the gas to react with an aqueous solution of potass

Natali5045456 [20]

Answer:

a) 2KI + O₃ + H₂O ----> I₂ + O₂ + 2KOH

b) Ozone concentration = 0.246 ppb

Explanation:

a) The balanced equation for the reaction is

2KI + O₃ + H₂O ----> I₂ + O₂ + 2KOH

b) We first convert 17 μg of KI to number of moles

Number of moles = (mass)/(molar mass)

Molar mass of KI = 166 g/mol

Mass of KI that reacted = 17 μg = (17 × 10⁻⁶) g

Number of moles = (17 × 10⁻⁶)/166

Number of moles of KI that reacted = (1.0241 × 10⁻⁷) moles

From the stoichiometric balance of the reaction,

2 moles of KI reacts with 1 mole of O₃

Then, (1.0241 × 10⁻⁷) moles of KI will react with (1.0241 × 10⁻⁷ × 1/2) moles of O₃

Number of moles of O₃ that reacted = (5.12 × 10⁻⁸) moles.

To express the amount of O₃ in 10.0 L of air in ppb, we need to convert the amount of O₃ that reacted.

Mass = (number of moles) × (molar mass)

Molar mass of O₃ = 48 g/mol

Mass of O₃ that reacted = (5.12 × 10⁻⁸) × 48 = 0.0000024578 g = (2.46 × 10⁻⁶) g

Concentration in ppb = (Mass of solute in μg)/(volume of solution in L)

Mass of solute = Mass of O₃ = (2.46 × 10⁻⁶) g = 2.46 μg

Volume of solution = 10.0 L

Concentration of O₃ in air in ppb = 2.46/10 = 0.246 ppb

4 0

3 years ago

What can I do to improve my basic chemistry?

LUCKY_DIMON [66]

Answer:

read a lot and understand what you read

do practicals

4 0

3 years ago

Read 2 more answers