Why are no flying dinosaur fossils found in rocks that are younger than those
formed during the Mesozoic era?

From the calculations, the value of x is found to be 7.

The anhydrous salt is the salt that does not contain the water of crystallization.

We know that;

Number of moles of anhydrous salt = number of moles of hydrated salt

Number of moles of anhydrous salt = 77.5g/155 g/mol = 0.5 moles

Number of moles of hydrated  NiSO4= 140.05g/155 + 18x

Thus;

0.5 = 140.05g/155 + 18x

0.5 (155 + 18x) =  140.05

77.5 + 9x = 140.05

x =  140.05 - 77.5 /9

= 7

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Answer:

The double bond is shown conventionally by two lines joining the atoms. Each line represents one pair of shared electrons. Carbon dioxide, CO2 Ethene, C2H4 Ethene has a double bond between the two carbon atoms. A more sophisticated view of the bonding in ethene

Explanation:

Answer:

12.5 gm left

Explanation:

30 minutes is THREE half lives

   1/2^3 = 1/8th   would be left

100g * 1/8 = 12.5 gm

Due to the fact that the half-life of the isotope is just 10 minutes, there will be 12.5 grammes of the original sample, which weighed 100 grammes, left after 30 minutes.

We can use the half-life to figure out how much of the isotope is left after 30 minutes by looking at how it breaks down.

A radioactive isotope's half-life is the amount of time it takes for half of the original sample to decay. In this case, 10 minutes is the half-life.

After 10 minutes, 50 g of the isotope will be left from the 100 g sample because 50 g of it will have decayed. Now, the first half-life has come to an end.

After another 10 minutes (for a total of 20 minutes), half of the leftover 50 g will decay, leaving us with 25 g of the isotope.

After another 10 minutes, for a total of 30 minutes, half of the 25 g that is still there will decay, leaving us with 12.5 g of the isotope.

So, there will be 12.5 grammes of the isotope left from the 100 g sample after 30 minutes.

It's important to keep in mind that the process of decay is exponential. With each passing half-life, the amount of isotope that is left drops by half. Because of this, it takes longer and longer for the amount of isotope that is left to decrease significantly, but it will never hit zero.

Understanding the idea of "half-life" is important in many areas of science, such as atomic dating, nuclear medicine, and environmental science, because it helps figure out how fast radioactive materials break down and what effects they might have on living things and the environment.

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Answer:

I think it's..

Explanation:

You can explain more, please.

Answer:

This repulsion is stronger than the repulsion between the lone pair and the three bond pairs on the nitrogen atom. Since the repulsions on the bond pairs in H2O molecule are greater than that in NH3 the bond angle in water is less than that of ammonia.

Based on the given information, the given structures are isomers, i.e., option B as they have different arrangements, but the same molecular formula.

Isomers are organic compounds having the same molecular formula and different molecular structures.

This difference is due to varying spatial arrangement of atoms in the compounds.

Isomers of different compounds have different properties based on the molecular formula.

Thus, the correct option is B.

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A typical example of metal ore is copper which is used for production of electrical wires.

Metal ores are defined as the metals that are naturally deposited at the earth crust which can serve as a valuable resources for many industries.

The copper is a typical example of a metal ore which is a good conductor of electricity used for production of electrical wires.

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Answer:

Hope this helps :D

Explanation:

Metal: Aluminum and Copper

Non-Metal: Hydrogen and Flourine

Acid: Sulfuric Acid and Phosphoric Acid

Alkali Metals: Hydrogen and Lithium

Compounds: Water and Carbon Dioxide

Elements: Carbon and Oxygen

Answer:

I-123 and I-131

Explanation:

Radioactive iodine takes advantage of the fact that thyroid cells and thyroid cancer cells absorb iodine; therefore, it has been used to diagnose or treat various thyroid disorders. Iodine is made into two radioactive isotopes, I-123 and I-131, that are commonly used in patients with thyroid disease.

The answer is 42 grams of NaF are there in 1 mole.

A mole is defined as 6.022 × 10²³ atoms, molecules, ions, or other chemical units.

and the molar mass of a substance is defined as the mass of 1 mole of that substance, expressed in grams per mole.

It is equal to the mass of 6.022 × 10²³ atoms, molecules, or formula units of that substance.

Molar Mass , i.e. mass of 1 mole of NaF is sum of molar mass of Na and F

23 + 19

42 grams

Therefore 42 grams of NaF Sodium-fluoride are there in 1 mole.

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Intermolecular forces are the forces present between the molecules. In carbon dioxide the intermolecular force is LDM and in water, hydrogen, LDM, and dipole-dipole are present.

Molecular structures are the arrangement of the atoms in the three-dimensional phase of the molecule along with their electrons. Water has a bent shape while carbon dioxide has linear shape geometry.

Water is a polar covalent molecule that has hydrogen and dipole-dipole bonding and forces that makes them strong enough to make them liquid at RT. On another hand carbon dioxide is a nonpolar covalent molecule that is gas at room temperature.

Sodium chloride is an ionic compound that has anions and cations in it. As it has high lattice energy it remains solid at room temperature.

Therefore, water, carbon dioxide, and sodium chloride are at different phases at room temperature.

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Answer:

the answer is D

Explanation:

I hope it helps you

D. An electrolytic cell would be used to electroplate silver (Ag) on iron

(Fe).

To electroplate silver (Ag) on iron (Fe), an electrolytic cell would be used. In an electrolytic cell, electrical energy is used to drive a non-spontaneous chemical reaction, such as the deposition of silver onto the iron surface.

In the process of electroplating, the iron object serves as the cathode, where the reduction reaction occurs. The silver ions (Ag⁺) from the electrolyte solution are attracted to the cathode and are reduced to form solid silver (Ag) on the iron surface.

An electrolytic cell consists of two electrodes (anode and cathode) immersed in an electrolyte solution. The anode is typically made of the metal that will be dissolved or oxidized, while the cathode is the surface onto which the desired metal will be plated. In this case, the iron object would act as the cathode.

A dry cell (Option A) is a type of battery that produces electrical energy through a chemical reaction, but it is not suitable for electroplating. A voltaic cell (Option B) and a galvanic cell (Option C) are both types of electrochemical cells that produce electrical energy from spontaneous chemical reactions. However, they are not designed for the purpose of electroplating.

Only an electrolytic cell (Option D) allows the controlled deposition of one metal onto another by using an external power source to drive the desired reaction. Therefore, an electrolytic cell would be the appropriate choice for electroplating silver onto iron.

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Elements are now organized by increasing atomic mass. Hence, option B is correct.

The periodic table is a tabular array of chemical elements organized by atomic number.

Mendeleev's periodic table orders the elements based on their atomic mass whereas the Modern periodic table orders the elements based on their atomic number.

Hence, option B is correct.

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Answer:

See Below

Explanation:

mole weight of Au ( gold) = 196.97 gm

  31.1 / 196.97    = number of moles of Au

  Number of moles * Avagadro's Number = number of atoms

31.1 / 196.97      *    6.022 x 10^23 = 9.508 x 10^22 atoms

Answer:

A and D

Explanation:

The two answers to select would be A. (They experience frigid temperatures and harsh winds) and D. They have producers that live there.  Using process of elimination, it can't be option B. The Artic has 53 different species of land mammals, however the Antarctic does not. So that leaves you with A and D.

The statement that best explains why xenon has a higher boiling point than neon is that xenon has more electrons than neon.

The term intermolecular forces are the force that hold matter together in a particular state such as solid liquid or gas. The more the electrons present, the greater the polarizability and the greater dispersion forces at work.

Thus, the statement that best explains why xenon has a higher boiling point than neon is that xenon has more electrons than neon.

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Answer:

Radiation is the transfer of heat between objects which are not touching. I think

Explanation:

Answer:

The general formula for a straight chain alkane is CnH(2n+...so correct option is C and D

The statement 'photosynthesis and cellular respiration are opposite reactions' best describes the relationship between photosynthesis and cellular respiration.

Cellular respiration is a  chemical process where foods and oxygen are used to generate ATP in aerobic conditions.

Conversely, photosynthesis is a chemical process where light and carbon dioxide are used to generate chemical energy.

In conclusion, the statement 'photosynthesis and cellular respiration are opposite reactions' best describes the relationship between photosynthesis and cellular respiration.

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Answer:

B

Explanation:

The methyl prefix means theres a CH3 group bonded to a carbon in a hydrocarbon. This is called branching because it looks like a branched tree. This is literally cheating but you do you.

Answer:

Heat going into a substance changes it from a solid to a liquid or a liquid to a gas. Removing heat from a substance changes a gas to a liquid or a liquid to a solid.

Liquid → Gas: 

VaporizationGas → Liquid:

 CondensationSolid → Liquid:

 Melting or fusion

Solid → Gas: Sublimation

Explanation:

The mass of a NaCl solution that is required to prepare 0.40 L of a 0.75 M solution is 17.55g. Details about mass can be found below.

The mass of a substance can be calculated by multiplying the number of moles by its molar mass.

However, the number of moles of a solution must be initially calculated by using the following formula:

molarity = no of moles ÷ volume

no of moles = 0.75 × 0.40

no of moles = 0.3 moles

mass of NaCl = 0.3 × 58.5 = 17.55g

Therefore, the mass of a NaCl solution that is required to prepare 0.40 L of a 0.75 M solution is 17.55g.

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Answer:

a. 208g Bi

c. 0.0400g He

e. 2.38g U

b. 9.12g Mn

d. 1.40g N

Explanation:

I apologize in advance if any are incorrect. Hopefully this helps.

The practice that has been able to save some organisms from extinction is cross breeding.

Cross breeding is the process of producing separate strains of the same species in order to create new traits.

Living organisms are bound to go extinct when faced by certain unfavorable conditions that cannot be adapted to.

However, the production of resistant strains of the same species of an organism via cross breeding can help prevent them from going extinct.

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Answer:

c

Explanation:

Answer:

When sound wave hits the wall , some portion of the sound is reflected back to air which is converted into heat energy and

lost in the atmosphere and some of its transmitted through the walls.