how old was the oldest animal fossil
help thx
Answer:
the Rhyniognatha hirsti
Explanation:
at age 400 million years old
5.96 g of ammonia reacts completely according to the following reaction:
2 NH, (g) + Co, (g) → CN,OH, (s) + H20 (1)
(a) What is the theoretical yield of urea (CN,OH,) for this reaction?
(b) If 13.74 g of urea are produced, what is the percent yield for this equation?
please show work, will give brainliest
Explanation:
this explanation may help u to understand:)
Intramolecular forces of attraction are important in holding large molecules together.
a. True
b. False
Answer:
False. Intermolecular forces of attraction are important in holding large molecules together.
Explanation:
Within a molecule, atoms are held together by intramolecular forces. That is, intramolecular forces are the attractive forces that hold the atoms or ions that make up chemical substances (elements and compounds) together, forming a chemical bond.
On the other hand, intermolecular forces are those that act on different molecules or ions and that make them attract or repel each other. In other words, intermolecular forces are those that occur between the different molecules of a compound, and cause these molecules or ions to attract or repel each other.
So, intermolecular forces of attraction are important in holding large molecules together.
why is an alkaline substance dropped into lakes in some countries
Answer:
Lake Treatment
Explanation:
Sulphuric dioxide produced by industries and released into the atmosphere returns as acid rain or sulphuric acid. In lakes impacted by acid rain, such as in Ontario, Canada, the application of alkalis dropped by airplanes can control and neutralize the water's pH level.
20. What is an irreversible change?
Answer:
A change is called irreversible if it cannot be changed back again. For example you cannot change a cake back into its ingredients again. Irreversible changes are permanent.
Explanation:
Hope this helps!! :))
Refer to your completed Table 1d of the recitation guide of ionic compound naming rules to determine whether this statement is true or false. A Roman numeral in a compound name tells you how many of that ion appear in the formula. Select one: True False
Answer:
False
Explanation:
Roman numerals are seen in the names of several compounds. They often appear immediately after the name of central atom in the molecule.
These Roman numerals are used to depict the oxidation state of the central atom in the molecule and not to show how many of that ion appear in the formula.
For instance, in carbon IV oxide, the Roman numeral IV shows that the central atom in the compound-carbon is in the +4 oxidation state.
A hot air balloon has an air vent that keeps the air pressure inside and outside the same. Allen observes that a hot air balloon rises up when the gas molecules inside it are heated. Which
of the following laws is used to understand the behavior of the gas and why?
a) The high temperature brings the gas molecules closer together according to Charles's law because this law describes how a gas will behave at constant pressure
b) The high temperature makes the gas molecules spread apart according to Charles's law because this law describes how a gas will behave at constant pressure.
c) The high temperature lowers volume according to Boyle's law because this law describes how a gas will behave when the number of moles remains constant.
d) The high temperature ralses volume according to Boyle's law because this law describes how a gas will behave when the number of moles remains constant.
Answer:
B - The high temperature makes the gas molecules spread apart according to Charles's law because this law describes how a gas will behave at constant pressure.
Explanation:
Charle's Law describes the relationship between temperature and volume, where increased temperature leads to increased volume. When volume is increased, that means the gas molecules are more spread apart and have more random motion. Therefore, the answer is B.
The high temperature causes the gas molecules to spread apart according to Charles's law because explain how a gas, behave at constant pressure.
What does Charles law state?The physical principle called Charles' law which states that the volume of a gas equals a constant value many by its temperature as measured on the Kelvin scale.
Volume regaled by a clinched amount of gas is directly proportional to its temperature and pressure if remains steady.
Thus, option "B" is correct, the volume of a gas equals a constant value.
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13. What does the Law of Conservation of Mass state?
rank in order the strongest to the weakest acid cbr3cooh, ch3cooh and ccl3cooh
Answer: Rank in order the strongest to the weakest acid is [tex]CCl_{3}COOH[/tex] > [tex]CBr_{3}COOH[/tex] > [tex]CH_{3}COOH[/tex].
Explanation:
More readily a substance is able to donate a hydrogen ion more will be its acidic strength. Hence, stronger will be the acid.
More is the electronegativity of atoms attached to the acid more easily it will donate a proton. Hence, more will be its acidic strength.
Chlorine is more electronegative in nature as compared to bromine. So,
[tex]CCl_{3}COOH[/tex] is more acidic than [tex]CBr_{3}COOH[/tex].
Since there is no electronegative group attached to [tex]CH_{3}COOH[/tex] so it is least acidic than [tex]CCl_{3}COOH[/tex] and [tex]CBr_{3}COOH[/tex].
Thus, we can conclude that rank in order the strongest to the weakest acid is [tex]CCl_{3}COOH[/tex] > [tex]CBr_{3}COOH[/tex] > [tex]CH_{3}COOH[/tex].
In what form is energy that is NOT used for life processes released from living things?
1. Thermal energy
2. Chemical energy
3. Light energy
4. Sound energy
Answer:
Correct answer would be Option 2, Chemical Energy
Hope this helps!
A small coffee cup calorimeter contains 28.0 g of H2O at 19.73 oC. A 2.05 g sample of a metal alloy is heated to 98.88 oC and then placed in the water. The contents of the calorimeter come to a temperature of 21.23 oC. What is the specific heat of lead
Answer:
1.104 J/g°C
Explanation:
Using Q = m × c × ∆T
Where;
m = mass of substance (g)
c = specific hear capacity (J/g°C)
∆T = change in temperature (°C)
For a colorimeter,
Q(water) = - Q(metal)
m. c. ∆T (water) = - m. c. ∆T (metal)
According to the information provided;
For water:
m = 28.0g
c = 4.184 J/g°C
∆T = (21.23 - 19.73°C)
For the metal:
m = 2.05g
c = ?
∆T = (21.23 - 98.88°C)
m. c. ∆T (water) = - m. c. ∆T (metal)
[28 × 4.184 × (21.23 - 19.73°C)] = -[2.05 × c × (21.23 - 98.88°C)]
[117.152 × 1.5] = -[2.05 × c × (-77.65)]
175.728 = -[-159.1825c]
175.728 = 159.1825c
c = 175.728 ÷ 159.1825
c = 1.104
c = 1.104 J/g°C
Avagadro’s number:
A: Is constant irrespective of mass of the gases
B: Varies according to the mass of the gases
C: Varies according to the pressure on the gases
D: All of the Above
Answer:
A: Is constant irrespective of mass of the gases
Explanation:
Avagadro's number, denoted by nA, is a number that represents the units in one mole of any substance. The number is 6.02214076 × 10²³ and the units can be atoms, molecules, ions, formula units etc.
That is;
1 mole of a substance = 6.022 × 10²³atoms, molecules, ions, electrons etc.
It is important to note that the Avagyadro's number is constant irrespective of mass of the gases that are involved.
Having enough folic acid in your system by the early weeks of pregnancy is critical to prevent spina bifida.
Answer:
Yes.
Explanation:
Yes, enough folic acid in the body by the early weeks of pregnancy helps to prevent spina bifida. The body of woman uses folate during the pregnancy which produces red and white blood cells that help your baby to grow. Folate also lowers the risk of neural tube defect (NTD) in the unborn baby. Neural tube defect (NTDs) are the serious birth defects that greatly affect the spinal cord, brain and skull of the baby.
6. What is the total number of valence electrons in an
atom of germanium in the ground state?
Answer:
4⁺
Explanation:
Germanium (Ge) has an atomic number of 32 and belongs to group 14 on the periodic table. Germanium has an electronic configuration of [Ar] 3d¹⁰ 4s² 4p². There exist 32 electrons in its neutral atom. In fluorescent lights, germanium is utilized as a component of both alloys and phosphorus.
The electrons in the atom's outer shell are known as its valence electrons.
Thus, at the ground state, the outer shell of the Germanium atom has 4 electrons.
A molecule or ion that donates the hydrogen in a hydrogen bond is a hydrogen bond donor
a. True
b. False
Answer:
True
Explanation:
Hydrogen bonding is a type of intermolecular interaction that occurs when hydrogen is bonded to a highly electronegative atom.
We define the term ''hydrogen bond donor'' as the molecule that supplies the hydrogen atom in the hydrogen bond.
Hence, it is true that the molecule or ion that donates the hydrogen in a hydrogen bond is a hydrogen bond donor
What volume of 6.49 MHCl is needed to prepare 2.11 L of 1.07 MHCl? Your answer should have three significant figures.
Answer:
0.348 L
Explanation:
Step 1: Given data
Concentration of the concentrated solution (C₁): 6.49 MVolume of the concentrated solution (V₁): ?Concentration of the dilute solution (C₂): 1.07 MVolume of the dilute solution (V₂): 2.11 LStep 2: Calculate the volume of the concentrated solution
We want to prepare a dilute solution from a concentrated one. We can calculate the volume of the concentrated solution using the dilution rule.
C₁ × V₁ = C₂ × V₂
V₁ = C₂ × V₂ / C₁
V₁ = 1.07 M × 2.11 L / 6.49 M = 0.348 L
Gamma rays have the highest frequency among all common electromagnetic radiations. It means the gamma rays have the highest energy and the longest wavelength
Answer:
yes
Explanation:
cos of high electron transfer
(a) Describe the process by which Nitrogen is obtained from air on a large scale
The element nitrogen exists as a gas and is obtained from air on a large scale by fractional distillation of air.
What is an element?An element is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.
Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.
The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.
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The table shows the recipe and the available ingredients for making the maximum possible number of sandwiches.
Making Sandwiches
Recipe for One Sandwich:
2 cheese slices, 1 ham slice, 2 bread slices
Ingredients Available:
12 cheese slices, 10 ham slices, 12 bread slices
If the ingredients represent reactants of a chemical reaction, which of the following represents the leftover reactant?
A. 2 ham slices
B. 4 ham slices
C. 2 cheese slices
D. 4 cheese slices
Answer:
B. 4 ham slices
Explanation:
A chemical reaction involves one or more substances known as reactants combining chemically to give one or more substances known as products.
Reactants in chemical reactions combine in definite mole or mass ratios to give products. Therefore, when one substance is present in excess of what is required to combine with another to form products, that substance is known as the excess reagent. The other substance which is present in a smaller amount and which when used up, the reaction stops is known as the limiting reagent.
From the illustration of the sandwiches in the question, the recipe for one sandwich represents the chemical equation of a reaction. The equation form is given below:
2 cheese slices + 1 ham slice + 2 bread slices ---> 1 sandwich
The ratio of the reactant is 2 : 1 : 2
From the available ingredients, 12 cheese slices, 10 ham slices, 12 bread slices.
12 cheese slices will require 6 ham slices and 12 bread slices to produce 6 sandwiches.
However, since there are 10 ham slices, 4 ham slices will be left over unused. This is the excess or leftover reactant.
Answer:
B. 4 ham slices
Explanation:
Got it right on the test
The student adds 0.0010 mol of NaOH(s) to solution Y, and adds 0.0010 mol of NaOH(s) to solution Z. Assume that the volume of each solution does not change when the NaOH(s) is added. The pH of solution Y changes much more than the pH of solution Z changes. Explain this observation.
Answer:
The answer is in the explanation.
Explanation:
A buffer is defined as the aqueous mixture of a weak acid and its conjugate base or vice versa. Buffers are able to avoid the pH change of a solution when strong acid or bases are added (As NaOH).
Based on the experiment, it is possible that the solution Z was a buffer and Y another kind of solution. For this reson, pH of the solution Y changes much more than the pH of solution Z changes despite the amount of NaOH added is the same in both solutions.
Calcium has 6 different isotopic forms, listed with their fractional composition values, 40Ca-0.96941; 42Ca-0.00647; 43Ca-0.00135; 44Ca-0.2086 ; 46Ca-0.00004; and 48Ca-0.00187. Identify the most and least abundant isotopes of calcium.
Answer:
The most abundant isotope is ⁴⁰Ca and the least abundant is ⁴⁶Ca
Explanation:
The mass, in percentage, of eah isotope of Calcium is their fractional composition multiplied by 100:
40Ca-0.96941*100 = 96.941% of ⁴⁰Ca
42Ca-0.00647*100 = 0.647% of ⁴²Ca
43Ca-0.0013*100 = 0.13% of ⁴³Ca
44Ca-0.02086*100 = 2.086% ⁴⁴Ca
46Ca-0.00004*100 = 0.004% ⁴⁶Ca
48Ca-0.00187*100 = 0.187% of ⁴⁸Ca
That means the most abundant isotope is ⁴⁰Ca and the least abundant is ⁴⁶Ca
Reaction of 2,3-dimethyl-1-butene with HBr leads to an alkyl bromide, C6H13Br. On treatment of this alkyl bromide with KOH in methanol, elimination of HBr occurs and a hydrocarbon that is isomeric with the starting alkene is formed. What is the structure of this hydrocarbon, and how do you think it is formed from the alkyl bromide
Answer:
See explanation and image attached
Explanation:
The image attached shows the entire scheme of reactions mentioned in the question.
The first reaction is an addition reaction which yields a tertiary alkyl halide as shown in accordance with Markovnikov rule.
The second reaction is a dehydrohalogenation in which the base abstracts a proton from the alkyl halide followed by loss of a bromide ion to yield the corresponding alkene.
This alkene is an isomer of the starting material.
12. Which formula shows a substance that is not molecular?
H₂
H2O
н
CO2
Answer:
the answer is H ..............
someone answer please
Answer:
A
Explanation:
Which of the following explains the high boiling
point of water?
a Surface tension
b Polarity
C Capillary action
d Hydrogen bonding
Answer:
The correct answer is - d. hydrogen bonding.
Explanation:
Water has strong hydrogen bonds between its molecules that require a very high amount of energy in order to break. Water molecules are joined together or bound with a strong intermolecular force called hydrogen bonds.
These bonds require more kinetic energy which means more temperature or heat in order to break the bonds and turn into steam and this is the reason it has a high boiling point.
what elements don't form bonds
Answer:
Noble gases are a set of elements in the periodic table because they don't naturally bond with other elements. *Examples ...Helium; Neon; Radon; Xenon; Argon etc
Explanation:
theyre noble gases.
Arrange the following molecules in order of decreasing polarity of their bonds.
a. PBr3
b. SF2
c. H2O
d. NCl3
Answer:
SF2 > H2O > PBr3 > NCl3
Explanation:
Compare the electronegativity values for the atoms and classify the nature of the bonding based on the electronegativity difference.
P has an electronegativity of 2.1, while Br has an electronegativity of 2.96. The difference is 0.86, indicating that these atoms will form covalent bonds.
S has an electronegativity of 2.58 while F has an electronegativity of 4.0. The difference is 1.42, indicating that these atoms will form polar covalent bonds.
O has an electronegativity of 3.5 while H has an electronegativity of 2.1. The difference is 1.4, indicating that these atoms will form polar covalent bonds.
N has an electronegativity of 3.04, whereas Cl has an electronegativity of 3.5. This difference of 0.46 indicates that these atoms will form covalent bonds.
We know that the greater the electronegativity, the higher the polarity. In decreasing order of polarity, we have:
SF2 > H2O > PBr3 > NCl3
What are fluids? Why are they so called?
Fluids are liquid and gases. They take the shape of their containers. They are called fluids because of their ability to flow.
When using vacuum filtration to separate a dissolved solid from an undissolved solid, what techniques should you use to ensure a quantitative separation
Answer: See explanation
Explanation:
Vacuum filtration is referred to as a fast filtration technique that is used in the separation of solids from liquids. It is also used to collect a desired solid. It basically uses a side-arm flask and a Buchner funnel.
Based on the question, the techniques that should be used to ensure a quantitative separation goes thus:
• Wet the filter paper before the mixture is poured into the filter funnel.
• Then, carefully rinse the flask with a little amount of water into the filter funnel.
• After that, the solid on the filter paper should be washed the with a small amount of water.
• Finally, Dry the solid on the filter paper when the separation is done.
Dichlorine monoxide, Cl2O is sometimes used as a powerful chlorinating agent in research. It can be produced by passing chlorine gas over heated mercury (II) oxide according to the following equation: HgO + Cl2 ????HgCl2 + Cl2O What is the percent yield, if the quantity of the reactants is sufficient to produce 0.86g of Cl2O but only 0.71 g is obtained?
Answer:
% yield = 82.5%
Explanation:
HgO + 2Cl₂ → HgCl₂ + Cl₂O
Our reactants are:
HgO and Cl₂Our products are:
HgCl₂ + Cl₂OWe do not have information about moles of reactants, but we do know the theoretical yield and the grams of product, in this case Cl₂O, we have produced.
Percent yield = (Yield produced / Theoretical yield) . 100
Theoretical yield is the mass of product which is produced by sufficent reactant. We replace data:
% yield = (0.71 g/0.86g) . 100 = 82.5%
The percent % yield = 82.5%
The balanced chemical equation will be:
HgO + 2Cl₂ → HgCl₂ + Cl₂O
The reactants participating in this reaction are: HgO and Cl₂
The products so formed are: HgCl₂ + Cl₂O
[tex]\text{ Percent yield} = \frac{\text{Yield produced}}{\text{Theoretical yield}} *100[/tex]
The theoretical yield is the maximum possible mass of a product that can be made in a chemical reaction.
[tex]\text{Percent yield}= \frac{0.71 g}{0.86g} * 100 \\\\\text{Percent yield}= 82.5\%[/tex]
Thus, the percent yield is 82.5%.
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