answer this step by step pls

Answer:

neutrons = mass number - atomic number

. = 39-19 =20

Darwin observed __________________ types of mockingbirds and finches lived in different island environments.

11) When sodium metal is subjected to violet light, it causes the photoelectric effect. However, red light does not affect
the sodium. Explain this phenomena.

Which of the following is/are considered alcohols?
a CH3OH
b CH3CH2OH
C CH3CH2CH2OH
d All of the above

the electron configuration of an element describes _____.

A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme ________. folds to form secondary and tertiary structures interacts with water binds substrate is denatured by low pH

describe the development of the theory of atomic structure
this question is worth 6 marks

Atoms: SC.8.P.8.7

Match the definition to proper definition:

Term:

Definition:

1. Atoms

A.Positive subatomic particles found in the

nucleus of the atom

2. Neutron

B. Negative subatomic particle found in the cloud

3. Proton

C. Substance that has no electrical charge

4. Nucleus

D. Basic building block of all matter

5. Electron cloud

E. Substance that consists of only one type of ato,

6. Electrons

F. Center of an atom with a positive charge

G. Outside of the atom with a negative charge

7. Element

What were the first 5 planets that were observed? Why were those the only ones? Help pls!

What do all atoms in a period (horizontal rows) have in common?

for each type of geometry in the simulation, examine the resulting bond angles by clicking the show bond angles checkbox. based on your observations for each geometry, provide the bond angles at the indicated locations for the two-dimensional representations of the three-dimensional structures.

Question 1 (2 points)
Which option can be classified as a pure substance?

Question 1 options:

heterogenous mixture


solution


homogenous mixture


compound

Question 2 (2 points)
Law of conservation of mass states that:

Question 2 options:

matter is destroyed


matter does not change


matter is neither created nor destroyed


matter is created

Question 3 (2 points)
What is a property of bases?

Question 3 options:

all of the above


Sour taste


Slippery touch


Ability to form hydronium ions+

Question 4 (2 points)
Which property do solutions with low pH values have?


What does it mean to have a neutral pH? - Aseptic Health

Question 4 options:

have a -OH group


feels slippery


turns litmus paper blue


tastes sour

Question 5 (2 points)
How do the products of chemical reactions compare to their reactants?

Question 5 options:

The products often have completely different properties than the reactants.


The products are usually more toxic than the reactants.


The products usuallyhave more mass than the reactants.


The products usually have more atoms than the reactants.

Question 6 (2 points)
Which of the following is an example of a physical change?

Question 6 options:

Water freezing into ice.


A piece of wood burning.


A toy car rusting.


Zinc producing hydrogen gas when mixed with water.

Question 7 (2 points)
What might happen if you mixed a strong acid with an equally strong base?

Question 7 options:

You would see an explosive chemical reaction.


The base would destroy the acid.


You'd wind up with a pH-neutral salt and water.


The acid would destroy the base.

Question 8 (2 points)
In the equation shown, what are the reactants?

2H2+O2àH2O

Question 8 options:

Hydrogen and oxygen molecules (2H2 and O2 )


Ice crystals


Hydrogen atoms (H)


Water molecules (H2O)

Question 9 (2 points)
Which phrase most accurately describes a chemical change?

Question 9 options:

A change in form


A change in taste


A change on the molecular level


A change in appearance

Question 10 (2 points)
What does it mean when there is a physical change?

Question 10 options:

A new substance has been formed.


Matter has changed from one substance into a new substance.


Matter has changed size, shape or form


Matter has changed on the molecular level.

help pls ill give 20 points!

how might rising atmospheric co2 concentrations lower the ph of the oceans?

how many valence electrons are there in a magnesium atom?

Review the information from the documents you read for this assignment. Use what you learned to answer the following question. What were the major effects of a dust storm? Give your answer in at least four sentences.

Determine the pH of 7.53 x 10-4 mol/L calcium hydroxide solution

In the chloroplast, energy in sunlight is passed around different chlorophyll molecules until it reaches a specific chlorophyll molecule that can transfer energy in sunlight to an energized electron. This chlorophyll molecule is called the accessory pigment. electron-carrier molecule. nucleus. photoelectric point. reaction center.

what is the mass percent of hydrogen in water

JWhat type of evidence is gathering information through your senses or using scientific tools?

Predictions
Results
Scientific research
Observations

convert 120 mm to feet

What are the four groups of carbon compounds found in living things?

Elements in the same period in the same periodic table have the same ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

PLZ HELP i need it now

Lead has a density of 11.29 g/mL. If you had 186 g of lead, what would its volume be?

why are there no elementary substances that have the ionic bond?

how many electrons need to be lost or gained by Ca to attain noble gas electron configuration?

EASY QUESTION (PLEASE HELP THE INTERNET ISN'T SUCH A BIG HELP RIGHT NOW)
Things microscopes have helped scientists discover about cells.
(No links plz)

What is the average acceleration of the car between 24 and 40 seconds? Include the correct units.

Which of the following is the best definition of deposition in geology?(1 point)

A:the creation of volcanic rock when liquid magma hits the ocean and cools

B:the mixing of many layers of sediment by wind, water or ice


C:laying down of sediment in layers carried by wind, water or ice


D:the creation of any metamorphic rock

Study the chemical equation.
Na + Cl2 → NaCl
Is the chemical equation properly balanced?

what do you mean by decimal number system

please give answer​