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3 years ago

6

Based on the models, why do you think helium is number 2( the second element) and beryllium number 4( the fourth element) on the

periodic table?

1 answer:

Andrei [34K]3 years ago

8 0

The atomic number here refers to the number of electron that the atom has. helium only has 2 electrons and beryllium has 4 electron

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Which of the following types of radiation can penetrate the most deeply into your body?

ivolga24 [154]

Answer:

gamma rays

Explanation:

6 0

4 years ago

Read 2 more answers

A chemist dissolves 697. mg of pure potassium hydroxide in enough water to make up 160. mL of solution. Calculate the pH of the

umka21 [38]

<u>Answer:</u> The pH of the solution is 12.9

<u>Explanation:</u>

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

Given mass of KOH = 697 mg = 0.697 g (Conversion factor: 1 g = 1000 mg)

Molar mass of KOH = 56 g/mol

Volume of solution = 160 mL

Putting values in above equation, we get:

$\text{Molarity of KOH solution}=\frac{0.697\times 1000}{56\times 160}\\\\\text{Molarity of KOH solution}=0.0778M$

1 mole of KOH produces 1 mole of $K^+$ ions and 1 mole of $OH^-$ ions

To calculate the pOH of the solution, we use the equation:

$pOH=-\log[OH^-]$

We are given:

$[OH^-]=0.0778M$

Putting values in above equation, we get:

$pOH=-\log (0.0778)=1.11$

To calculate pH of the solution, we use the equation:

$pH+pOH=14\\pH=14-1.11=12.89$

Hence, the pH of the solution is 12.9

5 0

3 years ago

Base your answer on the information below and on your knowledge of chemistry.Nitrogen dioxide, NO₂, is a dark brown gas that is

vfiekz [6]

Answer:

There are two possible answers to the question

I) decreasing the pressure of the system

II) decreasing the temperature of the system

Explanation:

Looking at the equation of the reaction, it can be seen that the reaction is endothermic. This implies that decreasing the temperature favours the reverse reaction and more NO2 is produced.

Secondly, decreasing the pressure drives the equilibrium position towards the side having the higher total volume hence decreasing the pressure favours the reverse reaction and more NO2 is produced.

8 0

4 years ago

If you had 100 grams of wax(C25H52), predict...

marissa [1.9K]

Answer:

2 i think should be the correct answer

Explanation:

4 0

3 years ago

Place the following in correct sequence from simplest to most complex: 1. molecules 2. atoms 3. tissues 4. cells 5. organs

Lera25 [3.4K]

Answer:

Simplest to complex

Atoms, molecules, cells, tissues, organs

Explanation:

An atom is the smallest or basic unit of any substance or thing. therefore, it is simplest among given.

Two or more atoms joined together to form molecules. Therefore, molecules are complex than atoms.

Cell is the basic unit of life and a cell is made of many molecules and compounds. So, cells are more complex than molecules.

Several cells organised in a definite way to form tissue, so tissues are group of cells and perform a definite function inside a living thing. So, tissues are more complex than cell.

Organs consist of several cells and tissues and perform a specific functions. Therefore, organs are the most complex structure among given.

Therefore order from simplest to complex is as follows:

Atoms, molecules, cells, tissues, organs

6 0

4 years ago