Which statements describe the fossil record? Check all that apply.

There is very little fossil evidence for the first 4 billion years of Earth.
There is very little fossil evidence for the last 600 million years of Earth.
Most of the fossil evidence is from the first 4 billion years of Earth.
Most of the fossil evidence is from the last 600 million years of Earth.
The fossil record is complete.
The fossil record is not complete.

Answer:

This chemical equation represents a decomposition reaction. This identification is based on the fact that the single reactant chemical compound breaks down into two different chemical substances that are different from the initial chemical substance.

Explanation:

it was the sample response lol

A reactant is broken down into two or more products in the decomposition reaction. The given reaction is a decomposition reaction.

Decomposition reaction:

In this type of chemical reaction, a reactant is broken down into two or more products.

For example- Ammonium nitrate is broken down into nitrous oxide and water molecules.

[tex]\bold {NH_4NO_3 \rightarrow N_2O + 2H_2O}[/tex]

Therefore, the given reaction is a decomposition reaction.

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Answer:

HC2H3O2(I) + O2(g) ---> H2O(I) + CO2(g) ΔH= -72.35 kJ

Explanation:

We know that 5.0 g of acetic acid will contain, 5.0g/60 g/mol = 0.083 moles of acetic acid

Now from the reaction equation;

1 mole of acetic acid evolved -871.7 KJ of heat

0.083 moles of acetic acid will evolve 0.083 * -871.7 = -72.35 KJ

For 5.0 g of acetic acid, we can write;

HC2H3O2(I) + O2(g) ---> H2O(I) + CO2(g) ΔH= -72.35 kJ

Answer:

Explanation:

Solution required is .15 M 500 mL sodium fluoride .

molecular weight of sodium fluoride = 42

one mole of sodium fluoride = 42 grams

No of moles contained in the solution of .15M , 500 mL solution

= .15 x 0.5 moles = .075 moles

1 mole = 42 g

.075 moles = .075 x 42 = 3.15 grams .

So mass of sodium fluoride required = 3.15 g .

Answer:

D Nimbostratus

Explanation:

Answer: The state of maater for HgBr is solid.

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.  

A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.  

The balanced chemical equation is:

[tex]HgNO_3(aq)+KBr(aq)\rightarrow HgBr(s)+KNO_3(aq)[/tex]

Answer:

Explanation:

1 mole of oranges contains 6.02 x1023 oranges. 1 mole of helium gas contains 6.02 x1023 helium atoms. 1 mole of water contains 6.02 x1023 water molecules.

...

Answer:

25194.56

Explanation:

You'll  need a scientifuc calculator

2.91*10^22*1 = 2.91E22

2.91E22-/6.02*10^23=25194.56

6.02*10^22 Is the Mole number

Answer:

To some extent, yes

Explanation:

Answer:

Explanation:

4

Answer:

Explanation:

The trick here is to realize that if you know the volume of a gas at STP, you can use the fact that

1

mole of any ideal gas occupies

22.7 L

under STP conditions to calculate how many moles of gas you have in your sample.

Under STP conditions:

1 mole of an ideal gas = 22.7 L

−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

In your case, you know that your sample of gas occupies

2.28 L

under STP conditions, which are currently defined as a pressure of

100 kPa

and a temperature of

0

∘

C

.

This means that your sample will contain

2.28

L

⋅

molar volume of a gas at STP



1 mole gas

22.7

L

=

0.10044 moles gas

Now, the molar mass of the gas is the mass of exactly

1

mole of the gas. In your case, you know that you get

3.78 g

for every

0.10044

moles, which means that you have

1

mole

⋅

3.78 g

0.10044

moles

=

37.6 g

Since this is the mass of

1

mole of gas, you can say that the molar mass of the gas is

molar mass = 37.6 g mol

−

1

−−−−−−−−−−−−−−−−−−−−−−−

Answer:

1.58L

Explanation:

Given parameters:

Initial volume  = 1.2L

Initial temperature  = 28.5°C  = 28.5 + 273  = 301.5K

Final temperature  = 125°C  = 125 + 273  = 398K

Unknown:

New volume  = ?

Solution:

Volume and temperature relationship is resolved using the Charles's law.

The law states that "the volume of a fixed mass of a gas varies directly as its absolute temperature if the the pressure is constant".

So;

       [tex]\frac{V1}{T1}[/tex]    = [tex]\frac{V2}{T2}[/tex]  

V1 is the initial volume

T1 is the initial temperature

V2 is the new volume

T2 is the new temperature

             [tex]\frac{1.2}{301.5}[/tex]    = [tex]\frac{V2}{398}[/tex]    

              301.5V2  = 477.6

                       V2  = 1.58L

Answer: Reactant

Explanation:

In simple wording, Water act as a reactant and it broke or we can say split the larger molecule in the smaller ones, The H and OH bonds are attached to the two products that are formed after the reaction. Another process in which water is used as an important reactant is photosynthesis.

Answer:

community

Explanation:

Answer:

The correct answer is population. I took the test and got it right.

Answer: Mutations can cause instant adaptations, while natural selection is the process by which adaptations occurs over a series of generations. Adaptations are changes or processes of changes by which an organism or species becomes better suited for its environment. A mutation is an alteration of the DNA sequence.

Answer:

It’s false

Explanation:

it could be true if the question mentioned alkaline solution

Answer:

True

Explanation:

Phenolphthalein is colorless in the presence of an acid and turns pink in the presence of a base.

Answer:

it's easier to look it up

Explanation:

Answer:

See explanation

Explanation:

We know that surface area is an important determinant factor in the study of reaction rate. This is the reason why finely divided marble chips react faster than lumps of marble in the reaction between marble chips and dilute HCl.

Now imagine that i have a lump of marble and i have finely divided marble. Then i also have a solution of 0.5 M dilute HCl. If i introduce 1g of the lump  of marble into 250 ml solution of the 0.5 M HCl in one beaker and introduce 1g of finely divided marble into another 250 ml solution of 0.5 M HCl in a separate beaker, we will notice that the finely divided marble chips reacts faster as evidenced by the quicker effervescence of CO2 gas from the later compared to the former.

Hence, smaller marble chips reacts faster with dilute HCl than a lump of marble.

Answer:

yes the above given answer is absolutely correct I agree with u man on the above.

Answer:

1.725e+18

Explanation:

Answer:

85.155g NH3

Explanation:

Answer:

Explanation:

A cation with a 2+ charge will make a stronger ionic bond than a cation with a 1+ charge. A larger ion makes a weaker ionic bond because of the greater distance between its electrons and the nucleus of the oppositely charged ion.

Answer:

They will have the same ear shape since their proteins connect in the same ways to determine ear shape.

Explanation:

I majored in Chemistry

Answer:

They will have the same ear shape since their proteins connect in the same ways to determine ear shape.

Explanation:

Answer:

Electrons

Explanation:

Answer:

Electrons are not found in the nucleus for they are orbiting the atom.

Answer:

4

Explanation:

The following equation, which depicts the combustion of propane, is given in this question as follows:

C3H8 + 02 → CO2 + H2O

However, this equation is not yet BALANCED because the number of atoms of each element is not the same on the reactant and product side. To balance the equation, we make use of COEFFICIENT to ensure that the number of atoms of each element on both side correlates.

The balanced equation is as follows:

C3H8 + 502 → 3CO2 + 4H2O

Therefore, the coefficient for water (H2O) after balancing the equation is 4.

The study of chemicals is called chemistry.

The correct answer is D.

The equation is not yet BALANCED because the number of atoms of each element is not the same on the reactant and product sides.

To balance the equation, we make use of COEFFICIENT to ensure that the number of atoms of each element on both sides correlates.

After balancing the equation is as follows:

[tex]C_3H_8 + 50_2 → 3CO_2 + 4H_2O[/tex]

Hence, the correct answer is 4 which shows the balanced water.

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Answer:

Pseudoscience

Explanation:

Predicting the future based solely on the position of the planets is an example of pseudoscience.

Pseudoscience is a body of knowledge that is not based on the scientific method but on some unverifiable/unprovable claims.

Predictions about the future can only be valid if it is based on the scientific method, not just about the position of the planet. The scientific method involves observation, hypothesis formulation, testing of the hypothesis through repeatable experiments, and arriving at conclusion.

Any other statement or belief that is not based on these procedures is said to be pseudoscientific.

Answer:

The answer to your question is pseudoscience.

Explanation:

I took the module 1 exam and got it right, yesterday.

Answer: B

Explanation: A fluorine atom has nine protons and nine electrons, so it is electrically neutral. (neutral =0)

The nucleus of a fluorine atom has a charge of zero as the atom has equal number of positive and negative charges.

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Answer:

LiOH+CH3COOH=C2H3LiO2+H2O balanced equation

Explanation:

lithium hydroxide-> LiOH

hydrogen acetate->CH3COOH

lithium acetate->C2H3LiO2

water->H2O

LiOH+CH3COOH=C2H3LiO2+H2O

Li=1,O=3,H=5,C=2 --> Li=1,O=3,H=5,C=2

the two sides have same numbers so it is balanced.

The mass of an object is the product of its volume and density. The mass of a the object with a volume of 825 cm³ and a density of 13.6 g/cm³ is 11220 g.

Density of substance is the measure of its mass per unit volume. It describes how closely its particles are packed. Density depends on the bond type, temperature and pressure.

Volume of the object is the space occupied by its particles. Volume can be expressed in L, ml, cm³, dm³ etc. Only solids and liquids has a definite volume and the volume of gases is that of the container.

Give that, volume of the object = 825  cm³

density =  13.6 g/cm³

Mass = volume × density

m = 825  cm³ ×  13.6 g/cm³ = 11220 g

Therefore, the mass of the object is 11220 g.

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