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2 years ago

Which evidence best supports scientists' inferences about the origin and age of the universe?

Chemistry

2 answers:

dsp732 years ago

6 0

Answer:

The answer is cosmic background radiation.

Explanation:

Background cosmic radiation is defined as the energy left over from the Big Bang, which produced the origin of the universe. This prediction was made by physicist George Gamow, Robert C. Herman, and Ralph A. Alpher.

Background cosmic radiation was first detected by radio astronomers Arno Penzias and Robert Wilson. The Big Bang theory predicted a specific characteristic of cosmic background radiation, which must be the spectrum of a body being in thermodynamic equilibrium. Through the COBE satellite it was possible to measure the spectrum of the cosmic background radiation and it was determined that this radiation is the same as the theory predicts.

BabaBlast [244]2 years ago

3 0

Do you have a picture for reference?

You might be interested in

According to the equation below, how many moles of Ca(OH)2 are required to react with 1.36 mol H3PO4 to produce Ca3(PO4)2? 3Ca(O

allsm [11]

<u>Answer:</u> The amount of calcium hydroxide needed to react is 2.04 moles

<u>Explanation:</u>

We are given:

Moles of phosphoric acid = 1.36 moles

For the given chemical equation:

$3Ca(OH)_2+2H_3PO_4\rightarrow Ca_3(PO_4)_2+6H_2O$

By Stoichiometry of the reaction:

2 moles of phosphoric acid reacts with 3 moles of calcium hydroxide

So, 1.36 moles of phosphoric acid will react with = $\frac{3}{2}\times 1.36=2.04mol$ of calcium hydroxide

Hence, the amount of calcium hydroxide needed to react is 2.04 moles

3 0

2 years ago

Describe how you would prepare exactly 100 mL of 0.109 M picolinate buffer, pH 5.61. Possible starting materials are pure picoli

Pepsi [2]

Answer:

1.342g of picolinic acid and 6.743mL of 1.0M NaOH diluting the mixture to 100.0mL

Explanation:

<em>The pKa of the picolinic acid is 5.4.</em>

Using Henderson-Hasselbalch formula for picolinic-picolinate buffer:

pH = pKa + log [Picolinate] / [Picolinic]

<em>Where [] could be taken as moles of each species</em>

<em />

5.61 = 5.4 + log [Picolinate] / [Picolinic]

0.21 = log [Picolinate] / [Picolinic]

1.62181 = [Picolinate] / [Picolinic] <em>(1)</em>

Now, both picolinate and picolinic acid will be:

0.100L * (0.109mol / L) =

0.0109 moles = [Picolinate] + [Picolinic] <em>(2)</em>

First, as we will start with picolinic acid, we need add:

0.0109 moles picolinic acid * (123.10g/mol) = 1.342g of picolinic acid

Now, replacing (2) in (1):

1.62181 = 0.0109 moles - [Picolinic] / [Picolinic]

1.62181 [Picolinic] = 0.0109 moles - [Picolinic]

2.62181 [Picolinic] = 0.0109 moles

[Picolinic] = 4.157x10⁻³ moles

And:

[Picolinate] = 0.0109 - 4.157x10⁻³ moles =

<h3>6.743x10⁻³ moles</h3><h3 />

To obtain these moles of picolinate ion we need to make the reaction of the picolinic acid with NaOH:

Picolinic acid + NaOH → Picolinate + Water

<em>That means to obtain 6.743x10⁻³ moles of picolinate ion we need to add 6.743x10⁻³ moles of NaOH</em>

<em />

6.743x10⁻³ moles of NaOH that is 1.0M are, in mL:

6.743x10⁻³ moles * (1L / 1mol) = 6.743x10⁻³L * 1000 =

<h3>6.743mL of the 1.0M NaOH must be added</h3><h3 />

Thus, we obtain the desire moles of picolinate and picolinic acid to obtain the buffer we want, the last step is:

<h3>Dilute the mixture to 100mL, the volume we need to prepare</h3>

3 0

2 years ago

What is the difference between calorie and Calorie?

Blababa [14]

What is the difference between calories and kilocalories? The "calorie" we refer to in food is actually kilocalorie. One (1) kilocalorie is the same as one (1) Calorie (upper case C). A kilocalorie is the amount of heat required to raise the temperature of 1 kilogram of water one degree Celsius.

5 0

2 years ago

How many moles of chromium metal equal 7.52 × 1022 atoms Cr?

grigory [225]

Answer:

0.125 mole

Explanation:

From Avogadro's hypothesis, we discovered that 1 mole of any substance contains 6.02x10^23 atoms.

The statement above suggests that 1 mole of chromium contains 6.02x10^23 atoms.

Now, if 1mole of of chromium contains 6.02x10^23 atoms,

Then Xmol of chromium contains 7.52x10^22 atoms i.e

Xmol of chromium = 7.52x10^22/6.02x10^23

Xmol of chromium = 0.125 mole

Therefore, 0.125 mole of chromium contains 7.52x10^22 atoms

8 0

2 years ago

A precipitate of zinc hydroxide can be formed using the reaction below.

worty [1.4K]

Answer:

Option B is correct. KOH is the limiting reagent, and 0.27 mole of Zn(OH)2 precipitate is produced.

Explanation:

Step 1: Data given

Number of moles ZnCl2 = 0.36 moles

Number of moles KOH = 0.54 moles

Step 2: The balanced equations

ZnCl2(aq) + 2 KOH(aq) → Zn(OH)2(s) + 2 KCl(aq)

For 1 mol ZnCl2 we need 2 moles KOH to produce 1 mol Zn(OH)2 and 2 moles KCl

Step 3: Calculate the limiting reactant.

KOH is the limiting reactant. It will completely be consumed (0.54 moles). ZnCl2 is in excess. There will react 0.54/2 = 0.27 moles

There will remain 0.36 - 0.27 = 0.09 moles.

Step 4: The products

There will be produced 2 moles KCl and 1 mol Zn(OH)2. Zn(OH)2 is the precipitate produced.

For 1 mol ZnCl2 we need 2 moles KOH to produce 1 mol Zn(OH)2 and 2 moles KCl

For 0.54 moles KOH, we will produce 0.27 moles precipitate (Zn(OH)2)

Option A is not correct because 0.27 mol of Zn(OH)2 will precipitate, not 0.54 mol

Option B is correct

Option C is not correct because ZnCl2 is not the limiting reactant, but the excess reactant

Option D is not correct because ZnCl2 is not the limiting reactant, but the excess reactant

7 0

2 years ago