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Answer:

Dmitri Mendeleev

Explanation:

Answer:

oxygen

Explanation:

Answer:

unsafe, solar

Explanation:

A lunar eclipse covers the moon which is safe to look at. New Moon, again is simply the moon. However, we should never look at the sun, eclipsed or not!

Answer:

C, it is unsafe to view solar

without eye protection

Explanation:

Volume = mass ÷ density

             =  116 g  ÷  0.925 g/mL

             =  125.41 mL

Answer:

Freezing the liquid

Explanation:

Freezing a liquid causes a liquid to become a soild.

Answer:

changing the temperature of the liquid

Explanation:

Ex. Cooking brownie batter(liquid), turns it into an edible brownie(solid). Ex. Putting water into a freezer freezes it, turning it into a solid.

Answer: B would be the correct answer

Explanation: You will need to use P1V1/T1=P2V2/T2

So

P1= 81.0kPa /101 =0.799atm

V1=0.4L

T1=25.0C +273.15K= 298.15K

P2= 101kPa /101 = 1atm

V2=0.25L

T2= ?

T2=P2V2T1/P1V1

(1.0atm)(0.25L)(298.15K)/(0.799atm)(0.4L) =233.22K-273.15=-39.92C

Answer:

Explanation:

2C7H6O2 + 15O2 → 14CO2 + 6H2O.

Answer:

C. H:C:H:H

Explanation:

Follow these simple steps to correctly draw a Lewis dot structure: Add up the total number of valence electrons found in the entire compound. Draw the simple structure (skeleton structure) of the compound by connecting everything with single bonds only. Add electrons to all the noncentral atoms. Put any unused electrons on the central atom.

Answer:

The atomic number equals number of protons and electrons

This is true when an atom is in neutral state.

Answer:

Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form.

Explanation:

Chemical change involves formation of new substances. Therefore, the correct answer is "Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form."

Explanation:

integral proteins...nns

Answer:

the bond that forms between carbon and oxygen to create carbon dioxide

A polar covalent bond

Answer:4

Explanation:

ANSWER : I AND III

HOPE IT HELPED

Explanation: It is an alloy, very probable, not homogeneous.

                  A metal paper clip is usually steel, an alloy of iron, carbon, and other elements in various amounts.  A plastic paper clip is composed of a polymer, a very complex compound.

                   A paper clip is a Colloid

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The two observations you would make about the atoms are

These observations were made by Ernest Rutherford in his model of the atom established in 1911, when he performed his gold foil experiment and observed the scattering angle of the alpha particles which led him to conclude that the mass of the atom was concentrated at the center.

Also, that most of the alpha particles also went through the gold foil suggested that the atom was made up basically of empty space.

So,

The two observations you would make about the atoms are

Learn more about the atom here:

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Answer:

i think it's a sedimentary rock...

reason:- these are the only rocks containing fossils

Explanation:

brainliest plz

The answers to the questions are as follows;

Question 1:

Since Nitrogen has 5 Valence electrons, it needs 3 electrons to attain it's octet configuration. As such, it gains 3 electrons.

Question 2:

The quantity which determines how two atoms bond is The difference in their electronegativities.

Question 3:

This is because the elements have filled Valence levels.

Question 4:

The ion which has a stable Valence electron configuration is potassium (K) with a 1+ charge

Question 5;

The chemical formula which represents a polyatomic ion is; ClO-

Answer:

They are not pure elements, instead they are compounds, hence why they are not found on the periodic table. (Periodic table only consists of pure elements)

Answer:

It can enhance survival because the animals for example birds are migrating to those places for high or increasing resources

Explanation:

Answer:

The water will eventually become the same temature (A)

Taking into account the definition of dilution, the concentration of the diluted solution is 0.063 M.

When it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

0.197 M× 2.42 mL= Cf× 7.55 mL

Solving:

(0.197 M× 2.42 mL)÷ 7.55 mL= Cf

0.063 M= Cf

In summary, the concentration of the diluted solution is 0.063 M.

Learn more about dilution:

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Answer:

D

Explanation:

Heterogeneous mixture is a mixture of non-uniform composition & in which the components can be easily identified

Answer:

Soil

Explanation:

Soil is made up of many things (therefore it's not pure) and does not appear to be uniform; it does not look the same throughout. Therefore it is heterogeneous.

Answer:

I would assume its the last one "The grass in the prairie provides oxygen, while animals give off carbon dioxide gas."

Explanation:

The question asks how the animals and plants rely on each other

The plants provide oxygen and food for the animals, and the animals provide carbon dioxide to them.

Hope this helps :D

Answer: During a chemical change, the composition of matter always changes

Explanation:

Answer:

The number of protons and electrons are equal.

Explanation:

When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is therefore zero and the atom is said to be neutral.

Taking into account the definition of ionization energy and electronegativity, you can say that the significance of the similarity of these trends  is that while electrons are more attracted to the nucleus (electronegativity), more energy is needed to extract an electron from a neutral atom (ionization energy).

Electrons are held in atoms by their attraction to the nucleus, which means that energy is needed to remove an electron from the atom.

Ionization energy, also called ionization potential, is the necessary energy that must be supplied to a neutral, gaseous, ground-state atom to remove an electron from an atom. When an electron is removed from a neutral atom, a cation with a charge equal to +1 is formed.

The further away the electron is from the nucleus, the easier it is to remove it, that is, the less energy is needed.

In a group the atoms have the same electronic structure in the outermost shell. But when going down in the same group, the electrons find themselves in shells that are farther and farther away from the nucleus, being less and less attracted. The size of the atom increases as the number of electronic shells increases, increasing the atomic radius when descending in a group. But the electrons are farther from the nucleus, and the easier it will be to expel them. That is, its extraction from the atom is facilitated. So the ionization energy decreases when descending in a group. In other words, ionization energy is a function of atomic radius; the larger the radius, the less energy is required to remove the electron from the outermost orbital.

By increasing the atomic number of the elements of the same period, the nuclear attraction on the outermost electron increases, since the atomic radius decreases and the effective nuclear charge on it increases.

For this reason, in a period, as the atomic number increases, the ionization energy becomes greater.

The electronegativity of an element is defined as the relative ability of an atom to attract electrons from another atom to chemically bond and form a compound.

In other words, electronegativity is a measure of the attractive force that one atom exerts on the electrons of another when a chemical bond forms.

In the groups, the electronegativity decreases from top to bottom because the valence shell moves away from the nucleus and with this the attraction that the nucleus exerts on the valence electrons decreases.

In the periods, the electronegativity increases from left to right, because the number of electrons in the valence shell increases, so the attraction of other electrons increases to complete the valence shell and reach a stable state.

The significance of the similarity of these trends  is that while electrons are more attracted to the nucleus (electronegativity), more energy is needed to extract an electron from a neutral atom (ionization energy).

Then, electronegativity is related to ionization energy in the following way: an atom with a high ionization potential has a high electronegativity. On the contrary, atoms with low ionization potential have small electronegativity.

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Answer:

1g Hydrogen

Explanation:

Calcium in water reacts vigorously to give a cloudy white Precipitate (compound) called Calcium hydroxide alongwith the evolution of Hydrogen gas.

[tex] \boxed{ \mathsf{Ca + H_2O \rightarrow Ca(OH)_2 + H_2}}[/tex]

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This reaction is not in it's balanced form! The number of atoms of Hydrogen on the left is 2 while that on the right is 4,I.e.,they're not equal.

Adding a 2 in front of H2O solves the problem by making the number of atoms of each element on both the sides equal.

[tex] \mathsf{Ca +2 H_2O \rightarrow Ca(OH)_2 + H_2}[/tex]

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Looking into the equation more carefully, we see:

1 atom of Calcium reacts with 2 molecules of water to give 1 molecule of Calcium Hydroxide alongwith 1 molecule of Hydrogen gas.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Mass of one atom of Calcium = it's gram atomic mass

= 40 g

Mass of one "molecule" of Hydrogen

= it's Gram molecular mass

= gram mass of one atom × number of atoms in one molecule

= 1 × 2

= 2 g

So,

according to our observation:

One atoms of Calcium gives one molecule of Hydrogen (during the particular reaction)

=> 40g of Calcium gives = 2g of Hydrogen

•°• 1 g of Calcium gives = [tex] \frac{2}{40} [/tex]

= [tex] \frac{1}{20} [/tex] g Hydrogen

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

We're provided with 20g of Calcium,

=> 20g of Calcium gives = 20 × [tex] \frac{1}{20} [/tex] g H2

= 1 g H2

_______________

Hope this helps!