Explain why the invention of the microscope led to the discovery of cells. ​

Answer:

Density 0.78945 g/cm3 (at 20 °C)

Melting point −114.14 ± 0.03 °C (−173.45 ± 0.05 °F; 159.01 ± 0.03 K)

Boiling point 78.23 ± 0.09 °C (172.81 ± 0.16 °F; 351.38 ± 0.09 K)

Solubility in water Miscible

Explanation:

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There is a golden role of solubility, polar solute dissolve in polar solvent and non polar solute dissolve in non polar solvent. Therefore, Salt and sand can be separated by dissolving the salt in water, filtering the mixture, and then evaporating the water to recover the salt.

Solutions are a homogeneous mixture of two or more substances. A solution is a homogeneous mixture of solvent and solute molecules. Solvent is a substance that is in large amount in solution.

Solute is the substance which is in small amount in a solution. Salt and sand can be separated by dissolving the salt in water, filtering the mixture, and then evaporating the water to recover the salt.

Therefore, Salt and sand can be separated by dissolving the salt in water, filtering the mixture, and then evaporating the water to recover the salt.

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Answer : The correct option is, Magnesium because it is a group 2 element with two valence electrons.

Explanation :

Element = Calcium

Atomic number = 20

Electronic configuration of Ca =  

Number of valence electrons in Ca = 2

The number of inner shell electrons in Ca = 18

This option is wrong because lewis-dot structure shows only valence electrons not inner shell electrons.

Element = Carbon

Atomic number = 6

Electronic configuration of C =  

Number of valence electrons in C = 4

This option is wrong because only outermost p-sublevel electrons are not showing in lewis-dot structure.

Element = Lithium

Atomic number = 3

Electronic configuration of Li =  

Number of valence electrons in Li = 1

This option is wrong because it has only 1 electron in outermost shell.

Element = Magnesium

Atomic number = 12

Electronic configuration of Ma =  

Number of valence electrons in Ma = 3

This option is correct.

Lewis-dot structure : It is defined as the structure in which valence electrons of the atom is shown as dots.

ANOTHER EXPLANATION:

Answer: C. Magnesium, because it is a group 2 element with two valence electrons.

An atom's Lewis dot structure has two dots. Which of the following elements could it be, and why?

A. Calcium, because it is an alkaline earth metal with two inner shell electrons.

B. Carbon, because it has two electrons in its outermost p sublevel.

C. Lithium, because it is a group 1 element with two bonding electrons.

D. Magnesium, because it is a group 2 element with two valence electrons.

Explanation:

If you were to look at the periodic table magnesium would be in group 2. Since magnesium is in group 2 therefore it will have two valence electrons. Calcium is another possible answer because it is also in group two, but for this quiz it is incorrect. Lithium is incorrect because it is in group 1 and therefore it would only have 1 valence electron. Carbon is also incorrect because it is in group 14 so it would have 4 valence electrons. Hope this helps and makes sense.

Good Luck!!

Have a great day Studying!

The Lewis dot structure of an atom has three dots. With three valence electrons and belonging to group 13, which of the following elements may it be?

The semi-metal boron (B) and the metals aluminum (Al), gallium (Ga), indium (In), and thallium (In) are all members of the boron family (Tl). The periodic table's fifth element, boron (Z=5), is found in Group 13. It is categorized as a metalloid because of its characteristics, which combine those of metals and nonmetals.

The Periodic Table of Elements places these elements in Group 13 (XIII) of the p block. Metallic elements include thallium, gallium, indium, and aluminum. In their outermost shells, they each have three electrons shell with the valence electron configuration ns2np1 (one electron in the p orbital and a complete s orbital).

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.

Answer:

1/8

Explanation:

[tex] \frac{1}{ {2}^{3} } = \frac{1}{8} [/tex]

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Answer:

ok you got it you just need to add.

Explanation:

add 5 times and she what you get.

Explanation:

Ethanol-filled thermometers are used in preference to mercury for meteorological measurements of minimum temperatures and can be used down to −70 °C (−94 °F). The physical limitation of the ability of a thermometer to measure low temperature is the freezing point of the liquid used.

Answer:9.38 x 10^−3 m

Explanation:

Answer: 9.38 x 10^−3 m

Explanation:

Answer:

There are 10 neutrons

Explanation:

Because the atomic number is 8 and the isotope number is 18 (which is the collective protons and neutrons), we can do

18-8=10

Answer:

10

Explanation:

8 proton because it is oxygen

10 neutron because 18-8

Answer:

The most common injury caused by working with machinery are cuts and burns.

Explanation:

Cuts and burns are the  most common injury caused by working with machines unsafely.

Any physiological harm to living tissue brought on by acute physical stress is referred to as an injury. An injury can be brought on by a blunt trauma, a piercing trauma, burning, exposure to chemicals, asphyxiation, or overexertion, and it can also happen accidentally. Any area of the body can become injured, and each injury has a unique set of symptoms.

Major injuries are normally treated by a medical practitioner, and the type of treatment depends considerably on the injury. The most frequent reason for accidental human injury or injury-related death is traffic crashes. Chronic conditions are different from injuries. Cuts and burns are the  most common injury caused by working with machines unsafely.

Therefore,  Cuts and burns are the  most common injury caused by working with machines unsafely.

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Answer:

is not completely ionized in water

The ethanoic acid (acetic acid) is considered as a weak acid because it does not releases all of its hydrogen in water, rather it dissociates partially and establishes an equilibrium with its conjugate base.

Answer:

The average kinetic energy increases, and the particles collide more frequently.

Explanation:

Answer:

see this

Explanation:

Answer:

129 units cubed

Explanation:

There are ten spaces between 120 and 130, so we can infer that each line represents a change in volume of 1 unit. The volume of the substance in the graduated cylinder looks like it's 1 under 130, so its volume is 129 units.

Hopefully this was helpful! :)

Answer:

a hydrogen ion will have more or fewer electrons than a standard hydrogen atom.

Explanation:

ions are atoms that have lost or gained elections. this applies to ions in general.

Answer:

number 29 is D

Explanation: When the moon orbits the earth some of the light reflects off the moon, making it visible on the Earth.

I dont know how to answer 28 fully, is there a picture?

Answer:

A substance that has a fixed chemical composition throughout is called a pure substance such as water, air, and nitrogen. A pure substance does not have to be of a single element or compound.

Explanation:

Compound: A substance that contains more than one element

pure substance: is made up of one substance made up of only one type of molecule

Answer: the answer should be A the first one

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Answer:

Valency of nitrogen in the given compounds:

N₂O₃ = +3

N₂O₅ = +5

NO = +2

-TheUnknownScientist 72

Answer:

Yes.

Explanation:

Answer:

=0=0==00=0=0=

Explanation:

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Answer:

Covalent bond between identical atoms

Covalent bonds occur between identical atoms or between different atoms whose difference in electronegativity is insufficient to allow transfer of electrons to form ions. ... The two hydrogen atoms are attracted to the same pair of electrons in the covalent bond.

Answer:

Sn has a different charge in each of the compounds.

+2, +4 charges, respectively.  

Explanation:

SnO has subscripts of 1, which means it takes only one of each element to make the compound.

We know that oxygen's charge is -2 from the periodic table.

In order for the compound to be neutrally charged,

Sn + O = 0

Sn - 2 = 0.

So, Sn has a +2 charge.

Likewise with the second compound, we know O has a -2 charge.

Sn + 2*(-2) = 0

Sn - 4 = 0

Sn = +4

+2 and +4 are different charges on the Sn cation.  

Answer:

strong winds come from the energy of a hurricane

The energy of a hurricane come from strong wind. The Taino Native American term hurricane, which translates to "bad spirit of the wind," is where the word hurricane originates.

A tropical storm that has sustained winds of 74 mph or greater is referred regarded as a hurricane. A storm's eye typically measures 20 to 30 miles in width and can reach distances of 400 miles. Storms can be dangerous because of their torrential downpours, strong gusts, and storm surges.

When warm, humid air begins to rise over water, hurricanes emerge. Cooler air replaces the rising air. Large clouds and thunderstorms continue to grow as a result of this process. Thanks to the earth's Coriolis Effect, these thunderstorms are still expanding and starting to rotate.

Thus, option B is correct.

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Answer:

ACID RAIN

Explanation:

duh

Answer:

Lithium has 1 valence electron, Sulfur has 6

A is oxidized, B is reduced

A is reducing agent, B is oxidizing agent

Explanation:

when an atom loses electrons, it is oxidized

when an atom gains electrons, it is reduced (almost think of when you add a negative number to a positive number, the positive number gets smaller or is reduced)

Answer:

The convection zone :)

Answer:

the ability of a compound to dissolve

Explanation:

salt dissolves in water so it would be soluble.

oil does not dissolve in water so it is not soluble

Answer: 57.C

Explanation: simple subtraction