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stiks02 [169]
3 years ago
13

What is an atom? A- the smallest particle of an element. B- the negatively charged particle found in a cloud. C- the densely pac

ked center of an element. D- An energy level with positive and negative charges

Chemistry
2 answers:
riadik2000 [5.3K]3 years ago
6 0
The answer is A! Hope this helps
cestrela7 [59]3 years ago
5 0

Answer:

A

Explanation:

it is the most basic unit of matter

You might be interested in
List first thirty elements with their valences​
lbvjy [14]

Element   Atomic Number Valency

Valency of Hydrogen 1 1

Valency of Helium 2 0

Valency of Lithium 3 1

Valency of Beryllium 4 2

Valency of Boron 5 3

Valency of Carbon 6 4

Valency of Nitrogen 7 3

Valency of Oxygen 8 2

Valency of Fluorine 9 1

Valency of Neon 10 0

Valency of Sodium (Na) 11 1

Valency of Magnesium (Mg) 12 2

Valency of Aluminium 13 3

Valency of Silicon 14 4

Valency of Phosphorus 15 3

Valency of Sulphur 16 2

Valency of Chlorine 17 1

Valency of Argon 18 0

Valency of Potassium (K) 19 1

Valency of Calcium 20 2

Valency of Scandium 21 3

Valency of Titanium 22 4

Valency of Vanadium 23 5,4

Valency of Chromium 24 2

Valency of Manganese 25 7, 4, 2

Valency of Iron (Fe) 26 2, 3

Valency of Cobalt 27 3, 2

Valency of Nickel 28 2

Valency of Copper (Cu) 29 2, 1

Valency of Zinc 30 2

5 0
2 years ago
Select all of the following equations that represent an exothermic reaction.
masya89 [10]

Answer:

C(graphite) → C(diamond), ΔH = - 0.45 kcal

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

Explanation:

C(graphite) → C(diamond), ΔH = - 0.45 kcal

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

These reactions are exothermic reaction because heat is evolved.

The energy changes occur during the bonds formation and bonds breaking.

There are two types of reaction endothermic and exothermic reaction.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O   →  CO  + H₂

ΔH = +131 kj/mol

it can be written as,

C +  H₂O  + 131 kj/mol  →  CO  + H₂

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂   →  CO₂ + 393 Kj/mol

6 0
3 years ago
Select all of the items that are true about a sample of water vapor at 101°C as it cools.
zloy xaker [14]

Answer:

D. Its temperature will remain 100 C until all the vapours condenses

Explanation:

Heat absorbed by a substance to change the state of matter is known as latent heat. This heat is utilized to break the bonds between atoms of the substance so that they can undergo phase change.

So, when water boils at 100 degree Celsius then temperature will remain constant unless and until all the water changes into vapor. As it is the latent heat that breaks the bonds between hydrogen and oxygen atoms of water so that liquid state can change into gaseous state.

Since latent heat is a hidden heat, that is why, it does not get reflected and there is no change in temperature due to it.

Thus, we can conclude that it is true that temperature will remain at 100°C until all the vapor condenses for a sample of water vapor at 101°C as it cools.

5 0
3 years ago
When strongly electronegative atoms, like fluorine, bond to atoms with a lower electronegativity, like hydrogen, what's the resu
olganol [36]
When highly electronegative element like oxygen is directly attached to less electronegative element like hydrogen the electrons from less electronegative elements are attracted toward the highly electronegative element, making the less electronegative element deficient in electron density (partial positive) and a partial negative charge on more electronegative element is created. In such situation the intermolecular forces formed are dipole-dipole interactions or hydrogen bond interaction like in HF.
7 0
3 years ago
A substance with a high [h ] would likely have which additional characteristics?
Ray Of Light [21]

Answer:

Is [h] really [H]?  What characteristics are mentioned?

Explanation:

A high [H} means high acid concentration.  

6 0
2 years ago
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