A student is studying calcium, a highly reactive element that humans need for strong bones. Which characteristic of calcium is most closely related to its chemical reactivity?
The 20 protons in each atom of calcium
The density of calcium, which is 1.54 g/cm3
The atomic mass of calcium, which is 40.078 amu
The 2 valence electrons in each atom of calcium

Answer: A-Nebulae can form stars, comets cannot

Explanation: Simply comets get destroyed and Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars.

While Nebulae is a body of interstellar cloud, made of cosmic dust, hydrogen etc , Comets are balls of rocks, frozen gases, that revolve the Sun.

Nebulae can form stars, but comets cannot. Option A is correct

Nebulae is a different body of interstellar cloud, they are made out of cosmic dust, hydrogen, helium, and molecular clouds.

While Comets are balls of rock, frozen gases, and other particles that revolve around the Sun.

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When hot water is placed in the bottom of the bottle and an ice cube is placed over the opening of the bottle, several observations can be made:

Condensation: The cold temperature of the ice cube causes the water vapor in the air inside the bottle to condense into liquid droplets on the surface of the bottle and the ice cube.

Evaporation: As the ice cube melts, it undergoes a phase change from solid to liquid, which increases the amount of water vapor in the air inside the bottle. This causes some of the liquid water droplets to evaporate back into water vapor.

Solid: The ice cube is a solid at room temperature, but it melts when it comes into contact with the hot water in the bottom of the bottle. The melting of the ice cube is an example of a solid undergoing a phase change to become a liquid.

Liquid: The hot water in the bottom of the bottle is a liquid and has a higher temperature than the ice cube. The liquid water in the bottom of the bottle transfers heat to the ice cube, causing it to melt.

Gas: Water vapor is a gas at room temperature, and it is produced by the evaporation of the liquid water droplets in the bottle.

Hence, the water vapor rises to the top of the bottle and can be seen as condensation on the inside of the bottle and the surface of the ice cube.

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Answer:

The answer is 101.1032

Explanation:

a) 2Mg + Pb(N\(O_{3}\)\()_{4}\)  → 2Mg(N\(O_{3}\)\()_{2}\) + Pb

b) 2Mg + Pb(N\(O_{3}\)\()_{4}\)  → 2Mg(N\(O_{3}\)\()_{2}\) + Pb

c) 2Mg (s) + Pb(N\(O_{3}\)\()_{4}\) (aq) → 2Mg(N\(O_{3}\)\()_{2}\) (s) + Pb (s)

d) This type of reaction is called displacement reaction.

What is displacement reaction?

In a displacement reaction, a portion of one reactant is exchanged out for another reactant. A displacement reaction is often referred to as a metathesis reaction or a replacement reaction.

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How is a nuclear change or reaction fundamentally different from a chemical reaction?

(1) Nuclear reactions involve a change in an atom's nucleus, usually producing a different element. Chemical reactions, on the other hand, involve only a rearrangement of electrons and do not involve changes in the nuclei. Hope this helps! :)

When investigating whether or not the substance dibromoethane (ethylene dibromide) is carcinogenic, we follow the survival history of 161 white employees of 2 factories who were exposed to dibromoethane.

Among them, we observe 7 cancer deaths in the period 1940-1975. On the other hand, the mean number of cases over that period in that general population is expected to be 5.8. Do those 7 cases provide a reason to consider the substance as .Yes, the seven cases provide a reason to consider the substance dibromoethane as carcinogenic.

Since the number of cancer deaths observed in the 161 white employees exposed to dibromoethane is 7 which is greater than the expected cancer deaths in the general population, which is 5.8. Therefore, the excess cases may suggest that dibromoethane has some carcinogenic potential.

Hence, we can consider dibromoethane as carcinogenic.

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The density of a block of wood that has a volume of 45 cm³ and a mass of 180 grams is 4g/cm³.

The density of a substance is the measure of the mass of matter contained in the substance by a unit volume.

The density of a substance can be calculated by dividing the mass of the substance by its volume i.e.

Density = mass (g) ÷ volume (mL)

According to this question, a block of wood that has a volume of 45 cm³ and a mass of 180 grams will possess a density of:

Density = 180g ÷ 45cm³ = 4g/cm³

Therefore, the density of a block of wood that has a volume of 45 cm³ and a mass of 180 grams is 4g/cm³.

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Answer:

Explanation:

Mass is a measure of the amount of matter in a substance or an object. The basic SI unit for mass is the kilogram (kg), but smaller masses may be measured in grams (g). To measure mass, you would use a balance. ... In that case, the fruit would have a mass of 1 kg, the same as the iron.

Answer:

option B and Option C

Taking into account the definition of molecular geometry, the correct option is option d.:  the bond angle of a linear molecule is 180 degrees.

In first place, molecular geometry or molecular structure is the spatial distribution of atoms around a central atom. Atoms represent regions where there is a high electron density, and are therefore considered electronic groups, regardless of the bonds they form.

That is, molecular geometry is the three-dimensional arrangement of the atoms that make up a molecule.

The molecular geometry of an element characterizes some of its physical or chemical properties, such as boiling point, viscosity, and density.

Linear molecules are molecules of the AB₂ type in which the central atom does not have lone pairs. To avoid repulsions between the binding pairs, arrange the B groups as far apart as possible. For that they must oppose each other 180 °.

In summary, linear molecular geometry describes the arrangement of different atoms with 180º bonds.

So, the correct option is option d.:  the bond angle of a linear molecule is 180 degrees.

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Answer:

Option B

Transfers energy to the water

Explanation:

Warm air transfers energy to the water when it flows over cold currents. This means that the warm air loses heat energy to the cold currents thus, raising its temperature.

Whenever there is a temperature difference between two bodies in contact with each other, the Fouriers law explains that there is always a transfer of heat from the hotter body to the colder body until they become the same temperature.

Thus, following this, heat will flow from the warm air to the cold currents.

The mass of a sample of platinum that has a volume of 3.50 cm³ and a density of 21.45 g/cm³ is 75.075 gm.

Solution :

∵ density = mass ÷ volume

so,  mass = density × volume

∴ mass of platinum sample = (density of sample) x (volume of sample)

                                             = 21.45 × 3.50

   mass of platinum sample = 75.075 gm

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The molarity of the calcium hydroxide solution is 0.0696 M

These are essentially 4-step problems.

1. Write and balance the equation. If we call potassium hydrogen phthalate just KHP, then

Ca(OH)2 + 2KHP ==> 2H2O + CaP + K2P

2. Convert grams to moles. moles KHP = 0.990/molar mass KHC8H4O4 = 0.990/179 = approximately 0.0055

3. Using the coefficients in the balanced equation, convert moles KHP to moles Ca(OH)2

0.0055moles KHP x (1 mole Ca(OH)2/2 moles KHP) = 0.0055 x (1/2) = 0.00275 moles Ca(OH)2.

4. M Ca(OH)2 = moles Ca(OH)2/L Ca(OH)2

 M Ca(OH)2 = 0.00275/0.0395 = approximately 0.0696 M

Part B is done the same way. Now that you have the Ca(OH)2 standardized, use that, with the same process, to determine the molarity of the HI.

Remember that moles = M x L.

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Answer:

The first one is Propane

The second one is HEPTANE

The third one is octane

The 4th is butane

the 5th is decane

The structures have been named according to IUPAC as \(\rm C_3H_8\) Propane, \(\rm C_7H_{16}\) Heptane, \(\rm C_8H_{18}\) Octane, \(\rm C_4H_{10}\) Butane, and \(\rm C_{10}H_{22}\) Decane.

The images has been the representation of the ball and stick structure of the compounds. The central balls have been the representation of the carbon atom , with small balls attached to the sticks have been the representation of the hydrogen attached.

The following structures has been given as:

The structures have been named according to IUPAC as \(\rm C_3H_8\) Propane, \(\rm C_7H_{16}\) Heptane, \(\rm C_8H_{18}\) Octane, \(\rm C_4H_{10}\) Butane, and \(\rm C_{10}H_{22}\) Decane.

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Answer:

Rabbit they eat plants for energy

Explanation:

Answer:

Clover

Explanation:

A clover is the only organism that makes its own food, usually from the sun. The other three need to eat to get their energy. Rabbits eat plants, owls eat insects, and hawks eat other types of animals such as fish.

The Ksp of cadmium sulfide, CdS, can be calculated using the molar solubility and the balanced equation for the dissolution of CdS in water. The balanced equation is:

CdS(s) ↔ Cd2+(aq) + S2-(aq)

The Ksp expression is:
Ksp = [Cd2+][S2-]
Since CdS dissolves in water to produce one mole of Cd2+ and one mole of S2-, the molar solubility of CdS can be used to find the concentration of Cd2+ and S2- in solution. The concentration of each ion is equal to the molar solubility, so:
[Cd2+] = [S2-] = 2.83 × 10−14 M
Substituting these values into the Ksp expression gives:
Ksp = (2.83 × 10−14 M)(2.83 × 10−14 M) = 8.00 × 10−28

Therefore, the answer is D. 8.00 × 10−28.

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A sample of nitrogen (9.27 g) reacts completely with magnesium, according to the equation: 3Mg + N2 --> Mg3N2. The mass of Mg consumed is 6.18 g.

To determine the mass of Mg consumed in the reaction, we need to use the stoichiometry of the balanced equation. The molar ratio between Mg and N2 is 3:1, meaning that 3 moles of Mg react with 1 mole of N2.

Given:

First, we need to convert the mass of N2 to moles. The molar mass of N2 is approximately 28.02 g/mol.

Moles of N2 = Mass of N2 / Molar mass of N2

Moles of N2 = 9.27 g / 28.02 g/mol

Moles of N2 ≈ 0.331 mol

According to the stoichiometry of the balanced equation, the ratio of Mg to N2 is 3:1. Therefore, the moles of Mg consumed will be three times the moles of N2.

Moles of Mg = 3 * Moles of N2

Moles of Mg = 3 * 0.331 mol

Moles of Mg ≈ 0.993 mol

Finally, we can calculate the mass of Mg consumed using its molar mass, which is approximately 24.31 g/mol.

Mass of Mg consumed = Moles of Mg * Molar mass of Mg

Mass of Mg consumed = 0.993 mol * 24.31 g/mol

Mass of Mg consumed ≈ 24.00 g

Therefore, the mass of Mg consumed in the reaction is approximately 6.18 g.

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Explanation:

It's a distance-time graph showing the speed of an object

Answer:

You become negatively charged

Answer:

Trichloroethane is a solvent used to remove grease from clothes.

Explanation:

here's the answer to your question

The percentage of this compound  Mg(OH)2 which is oxygen with atomic mass of an atom of oxygen is 15.999 amu is 54.9%.

Percentage by mass is a way of representing the concentration of an element in a compound. It is calculated as the mass of the element divided by the total mass of the compound, multiplied by 100.

%O = 2*16/58.32 x 100 = 54.9%

The percentage of this compound is 54.9%

% Mg=24.30 /58.32×100%

=41.67%

% O=32.00 /58.32×100%

=54.87%

% H =2.016 /58.32×100%

=3.457%

The infinitesimal mass of an element is defined as the sum of the mass of the total number of protons and neutrons in an snippet. It's expressed as amu. For one operative of an element, the infinitesimal mass is expressed in g/ spook.

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An exothermic process called combustion necessitates the interaction of fuel with a reducing agent.

An object quickly reacts with oxygen in the chemical process of burning to produce heat. Fuel and oxygen's source are the terms used to describe the original substance. Although fuel for aeroplane propulsion is normally a liquid, it can also be a solid, liquid, or gas.

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Answer:

this

Explanation:

Molar mass also called Atomic mass is the atomic weight. You can find this on the periodic table.

-

-

The answer would be

A. the mass in grams of one mole of a substance

The molecule 2,3-dimethylheptane is chiral, whereas the molecules 3,3-dimethylheptane, 2-methylheptane,3-methylheptane and 4-methylheptane are not chiral.

If molecule has a non-superimposable mirror image, then it a chiral molecule. If a molecule is superimposable on its mirror image, then it is not chiral.

The 3,3-dimethylheptane molecule has a plane of symmetry, making it possible to superimpose its mirror image on top of itself. It is therefore not chiral.

The 2,3-dimethylheptane molecule does not have a plane of symmetry, thus its mirror image cannot be superimposed on itself. Therefore, it is chiral.

The 2-methylheptane molecule does not have a plane of symmetry, but it does have a rotational axis of symmetry that allows for the superposition of its mirror image. Therefore, it is not chiral.

The 3-methylheptane molecule does not have a plane of symmetry, but it does have a dihedral plane of symmetry that can be used to superimpose its mirror image on itself. Therefore, it is not chiral.

The 4-methylheptane molecule does not have a plane of symmetry, but it does have a rotational axis of symmetry that allows for the superposition of its mirror image. Therefore, it is not chiral.

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Answer:

4.0 moles

Explanation:

Based on the given reaction between carbon and hydrogen, the equation of the reaction between O₂ and CO is as follows:

2CO(g) + O₂(g) → 2CO₂(g)    

The number of moles of O₂ needed to completely react with 8.0 moles of CO can be calculated knowing that 2 moles of CO react with 1 mol of O₂:

\( n_{O_{2}} = \frac{1 mol O_{2}}{2 moles CO}*8.0 moles CO = 4.0 moles O_{2} \)

Therefore, the number of moles of O₂ needed is 4.0.

I hope it helps you!