Please can I have help on these two questions I’ll be very grateful!!!!!!

Answer:

D

Explanation:

Option D gives the correct model of C7H16. From the option, one will discover that the model has 7 carbons in the backbone. If you count the attached hydrogen, you will discover that the hydrogen is 16 in total.

This model or skeletal structure of this element represents heptane. Heptane or n-heptane is known to be a straight-chain compound and an alkane. It's chemical formula can also be written as: H₃C(CH₂)₅CH₃ or C₇H₁₆.

This compound is known to be one of the main components of gasoline. It is known to be a volatile organic compound and a clear and colorless liquids with a petroleum-like odor.

Answer: D

Explanation: Just took the test

The disease can slow the predator down and the prey can get away easily.

Answer:

Radio is used primarily for communications including voice, data and entertainment media.

Answer:

Carbon, Hydrogen, Oxygen

Explanation:

From the prefix "macro" which means large, macromolecules are considered to be "large molecules" when compared to the micromolecules. They come in four major types: proteins, nucleic acids, carbohydrates and lipids.

These macromolecules have three common elements and these are: Carbon, Hydrogen and Oxygen. These are all essential in the vitality of life. The human body is said to have 10% of carbon and 63% oxygen. Hydrogen, on the other hand, is said to be the most abundant element among organic molecules.

Answer: B) Crash 2; the force on the cart was stronger in this crash, so the force on the skateboard was also stronger.

Explanation:

Skateboards are subjected or experience to a greater force in Crash 2.

The force applied on the cart 2 was stronger or powerful in this collision 2, thus the force or power on the skateboarding was also higher and greater, according to the statement.

Strong forces usually do more damage to specific items or things.

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Answer:

Hot air rises. Heated air molecules “spread out” or expand and bounce around, and the space becomes less dense than the surrounding space. Increasing the air temperature inside the balloon envelope makes it less dense than the air, thus making it “lighter than air”.

Explanation:

I'm new to brainly but I hope this helped!

Balloon rise because  Warm air ascends. Heat causes the molecules of the air to "spread out," or expand, and bounce off one another, making the area less dense than the surroundings.

What are molecules ?

A molecule is the smallest unit of a substance that keeps its content and properties. It is made up of two or more atoms that are joined together by chemical bonds.

Chemistry is built on molecules. The element symbol and a subscript indicating the number of atoms are used to identify molecules.

When Balloon rise because  Warm air ascends. Heat causes the molecules of the air to "spread out," or expand, and bounce off one another, making the area less dense than the surroundings.

The air inside the balloon's envelope becomes less dense as the temperature rises, making it "lighter than air."

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Answer:

The only reason wood floats is because it is less dense and has big openings and gaps which allows air in.

Wood that sinks has very tiny openings. The ratio between weight and volume is called density. An object that is less dense than water can be held up by water, and so it floats.

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Answer:

mechanical or kinetic eg hammer and nails

Answer:

Phosphorus trioxide

Explanation:

Answer:

Tetraphosphorus hexoxide

Explanation:

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Answer:

oceanic ridge

The youngest rocks on the ocean floor are located at the oceanic ridge, an underwater mountain range formed from the spreading of tectonic plates in.

Explanation:

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Answer:

Aa 50% Widow's peak, aa 50% no Widow's peak

Explanation:

In the crossing over the phenotypes of their children, 50% are widow's peak (aa), while 50% are not widow's peak (Aa) because the widow's peak genes only show trait when it is in recessive condition.

An inheritance pattern known as autosomal recessive inheritance allows a genetic disease or characteristic to be transferred from parent to offspring.

When a kid receives one altered (mutated) gene from each parent, a genetic disease may result. An autosomal recessive disorder is typically not present in the parents of a kid who has it.

Describes a property that can only be observed when a genotype is homozygous, a feature that is often concealed by other inherited qualities but survives in a population of heterozygous genotypes.

The crossing between Aa X Aa

Gametes: A and a.

The cross is attached in the image below.

Therefore, the gene's dominant allele, which is expressed when its alleles are distinct, is the case when the alleles are different. The recessive allele effect is hidden by the other allele's effect.

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Answer:

sulfur

Explanation:

From the given lists of elements, the one with the most electronegativity is Sulfur.

  Electronegativity is of an element is a property that combines the ability of its atom to lose and gain electrons.

It is a measure of the relative tendency with which the atoms of the element attract valence electrons in a chemical bond.

Using the Pauling's electronegative table of elements;

   Here are electronegativity values of the given elements;

selenium                 2.4

arsenic                    2.0

phosphorus            2.1

sulfur                      2.5

We see that the value of sulfur is the highest.

Answer:

A) Energy and Water molecules are free to escape into the surrounding environment.

Explanation:

Hello! This is the correct answer! (I took the K12 test)  

I hope this helps!  Have a blessed day! :)

When boiling a pot of water on the stove without a lid on the pot, the energy and water molecules are free to escape into the surrounding environment.

Boiling point of a substance is the temperature at which the substance changes from liquid state to gaseous state where these two systems comes in equilibrium.

Thus when a liquid is boiled, the liquid molecules get more energy to move apart and they escape into gaseous state. With change in state of the substance, the energy also be transferred from the liquid to the environment.

If the pot is closed with a lid, then both energy can be transferred but molecules get trapped inside. But here the pot is open and thus the gas molecules and energy are free to move outside.

Therefore, option A is correct for the boiling of water in an open pot.

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Answer:

3.05x10²³ (3 sig. fig.)

Explanation:

Propane (C₃H₈) is a colorless alkane gas with three carbons and eight hydrogen atoms. In 2.23 grams of propane, there are 3.05 x 10²³ carbon atoms present.

The number of atoms or the particles being the smallest units is estimated by the product of the number of moles and Avogadro's number.

The Avogadro's number (Na) is used to determine the number of particles that have been present in a mole of a substance. A mole of a substance is said to have 6.022 × 10²³ ions, atoms, electrons, molecules, etc.

Moles of propane are calculated as,

Moles = mass ÷ molar mass

= 2.23 ÷ 440.094

= 0.05057

Now, the number of particles is calculated as,

Number = moles × Avogadro's number

= 0.05057 × 6.022 × 10²³

= 3.05 x 10²³

Therefore, 3.05 x 10²³ carbon atoms are present in 2.23 grams of propane.

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Answer:

76.2 L of [tex]CO_{2}[/tex]

Explanation:

Converting the unit of moles to liters is very easy if you know the value of a mole to a liter. Remember that 1 mole is equivalent to 22.413962 L.

Step 1:

3.4 mol [tex]CO_{2}[/tex] x 22.413962 [tex]\frac{liters}{mole}[/tex] = ?

Step 2:

Cancel out the moles.

Step 3:

If you multiply 3.4 by 22.413962, the answer is 76.2

Step 4:

Don't forget to put the units every time you answer. So the answer is: 76.2 L of [tex]CO_{2}[/tex]

Answer:

The fraction of original nuclei remaining is 1.5625

Explanation:

Answer:

magnesium. stronsium. barium. they are have similar group in IIA

Answer:

Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.

Answer:

• Copper chloride

• Copper (II) chloride

• Iron (II) sulfide

• Iron (III) sulfide

Answer:

C

Explanation:

Cyclohexane is a cycloalkane with the molecular formula C₆H₁₂. Cyclohexane is non-polar.

Answer : The volume of kristas rock is 30 mL.

Explanation :

From the given image we conclude that:

Initial volume of liquid = 150 mL

Final volume of liquid = 180 mL

Now we have to determine the volume of kristas rock.

Volume of kristas rock = Final volume of liquid - Initial volume of liquid

Volume of kristas rock = 180 mL - 150 mL

Volume of kristas rock = 30 mL

Therefore, the volume of kristas rock is 30 mL.

Answer:

cytoplasm

Explanation:

cytoplasm carries the nutrients of the cell

Answer:

Strontium

Explanation:

STRONTIUM

Strontium is a chemical element that is non radioactive and its occur naturally. It is a shiny and silvery white metal that have atomic number of 38 and it belong to group 2 member of the periodic table which is why it have two valence electrons. It is a solid metal at room temperature.

About 99% of Strontium is found in bones. It help to make new bones in humans by replacing the old bones.

Therefore, it is strontium.

Strontium is the element which is shiny, solid at room temperature and has two electrons in its outermost shell.

The atomic number of Strontium is 38. In the first shell, there are two electrons, in the second and fourth shell has space for 8 electrons so these shells are filled with electron whereas third shell has 18 electrons and the fifth shell has 2 electrons. Strontium belongs to second group i.e. alkaline earth metals due to which it has two valance electrons in its outermost shell.

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Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question we have

[tex]density = \frac{38.6}{2} \\ [/tex]

We have the final answer as

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Answer:

It sould be 250 grams

Explanation:

It is given that, 5 millimeter sample has the mass of 12.5 grams. Then, 100 millimeter sample have a mass of  250 g.

Mass of a substance is a physical quantity that describes the total amount of the substance. Mass is an extensive property since it depends on the change in amount or quantity of the substance.

The SI unit of mass is grams (g). Other units are kilograms, milligrams , pounds etc. Mass is of small substance is expressed in grams and that bigger things are usually expressed in kilograms.

Given that mass of 5 ml sample = 12.5 grams

then mass of 1 ml = 12.5/5 = 2.5 g

then mass of 100 ml = 2.5 × 100 = 250 grams.

Therefore, the mass of 100 ml of the sample is 250 g.

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