<h3>
Answer:</h3>
3.01 × 10²⁵ molecules H₂O
<h3>
General Formulas and Concepts:</h3>
<u>Math</u>
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Chemistry</u>
<u>Atomic Structure</u>
- Using Dimensional Analysis
- Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
<h3>
Explanation:</h3>
<u>Step 1: Define</u>
50.0 mol H₂O
<u>Step 2: Identify Conversions</u>
Avogadro's Number
<u>Step 3: Convert</u>
<u />
= 3.011 × 10²⁵ molecules H₂O
<u>Step 4: Check</u>
<em>We are given 3 sig figs. Follow sig fig rules and round.</em>
3.011 × 10²⁵ molecules H₂O ≈ 3.01 × 10²⁵ molecules H₂O
<span>There are three atoms of Sn (Stannous or Tin) in</span> 356.13 g of Sn.
<span>One atom of Sn has the atomic mass (m</span>ₐ<span>) of </span>118,71u which means:
356.13/118.71=3 atoms of Sn
The mass number (symbol A) also called atomic mass number or nucleon number is the total number of protons and neutrons in an atomic nucleus. It determines the atomic mass of atoms and it is in the periodic table.
Answer : The value of
for the reaction is, -565.6 kJ
Explanation :
First we have to calculate the molar mass of CO.
Molar mass CO = Atomic mass of C + Atomic mass of O = 12 + 16 = 28 g/mole
Now we have to calculate the moles of CO.

Now we have to calculate the value of
for the reaction.
The balanced equation will be,

From the balanced chemical reaction we conclude that,
As,
of CO release heat = 10.1 kJ
So, 2 mole of CO release heat = 
Therefore, the value of
for the reaction is, -565.6 kJ (The negative sign indicates the amount of energy is released)
It respresents the higher energy level than 627nm .
<h3>What is a emission line ? </h3>
Emission lines are the glowing hot gas emits lines of light whereas absorption line refers to the tendency of cool atmospheric gas to absorb the same line of light.Some lights produce dark band when the light passes through gas in the atmosphere . There are two line spectrum and absorption.
spectrum is an excitement of electrons from lower to higher energy levels and when it comes back it releases energy in the terms of colourful lights .
It represents the higher energy levels than 627nm because Energy is inversly proportional to wavelength .
to learn more about Emission lines click here
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Answer: 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide, 
Explanation:
The reaction equation for given reaction is as follows.

Here, 1 mole of
reacts with 3 moles of
.
As mass of chromium (III) oxide is given as 76 g and molar mass of chromium (III) oxide
is 152 g/mol.
Number of moles is the mass of substance divided by its molar mass. So, moles of
is calculated as follows.

Now, moles of
.given by 0.5 mol of
is calculated as follows.

As molar mass of
is 2.016 g/mol. Therefore, mass of
is calculated as follows.

Thus, we can conclude that 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide,
.